//------------------------------------------------------------------------------
// <copyright file="OleDbCommand.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
// <owner current="true" primary="false">Microsoft</owner>
//------------------------------------------------------------------------------

namespace System.Data.OleDb {

    using System;
    using System.ComponentModel;
    using System.Data;
    using System.Data.Common;
    using System.Data.ProviderBase;
    using System.Diagnostics;
    using System.IO;
    using System.Runtime.CompilerServices;
    using System.Runtime.InteropServices;
    using System.Security;
    using System.Security.Permissions;
    using System.Threading;
    using System.Text;

    [
    DefaultEvent("RecordsAffected"),
    ToolboxItem(true),
    Designer("Microsoft.VSDesigner.Data.VS.OleDbCommandDesigner, " + AssemblyRef.MicrosoftVSDesigner)
    ]
    public sealed class OleDbCommand : DbCommand, ICloneable, IDbCommand {

        // command data
        private string _commandText;
        private CommandType _commandType;
        private int _commandTimeout = ADP.DefaultCommandTimeout;
        private UpdateRowSource _updatedRowSource = UpdateRowSource.Both;
        private bool _designTimeInvisible;
        private OleDbConnection _connection;
        private OleDbTransaction _transaction;

        private static int _objectTypeCount; // Bid counter
        internal readonly int ObjectID = System.Threading.Interlocked.Increment(ref _objectTypeCount);

        private OleDbParameterCollection _parameters;

        // native information
        private UnsafeNativeMethods.ICommandText _icommandText;

        // if executing with a different CommandBehavior.KeyInfo behavior
        // original ICommandText must be released and a new ICommandText generated
        private CommandBehavior commandBehavior;

        private Bindings _dbBindings;

        internal bool canceling; // MDAC 68964
        private bool _isPrepared;
        private bool _executeQuery;
        private bool _trackingForClose;
        private bool _hasDataReader;

        private IntPtr _recordsAffected;
        private int _changeID;
        private int _lastChangeID;

        public OleDbCommand() : base() {
            GC.SuppressFinalize(this);
        }

        public OleDbCommand(string cmdText) : this() {
            CommandText = cmdText;
        }

        public OleDbCommand(string cmdText, OleDbConnection connection) : this() {
            CommandText = cmdText;
            Connection = connection;
        }

        public OleDbCommand(string cmdText, OleDbConnection connection, OleDbTransaction transaction) : this() {
            CommandText = cmdText;
            Connection = connection;
            Transaction = transaction;
        }

        private OleDbCommand(OleDbCommand from) : this() { // Clone
            CommandText = from.CommandText;
            CommandTimeout = from.CommandTimeout;
            CommandType = from.CommandType;
            Connection = from.Connection;
            DesignTimeVisible = from.DesignTimeVisible;
            UpdatedRowSource = from.UpdatedRowSource;
            Transaction = from.Transaction;

            OleDbParameterCollection parameters = Parameters;
            foreach(object parameter in from.Parameters) {
                parameters.Add((parameter is ICloneable) ? (parameter as ICloneable).Clone() : parameter);
            }
        }

        private Bindings ParameterBindings {
            get {
                return _dbBindings;
            }
            set {
                Bindings bindings = _dbBindings;
                _dbBindings = value;
                if ((null != bindings) && (value != bindings)) {
                    bindings.Dispose();
                }
            }
        }

        [
        DefaultValue(""),
        Editor("Microsoft.VSDesigner.Data.ADO.Design.OleDbCommandTextEditor, " + AssemblyRef.MicrosoftVSDesigner, "System.Drawing.Design.UITypeEditor, " + AssemblyRef.SystemDrawing),
        RefreshProperties(RefreshProperties.All), // MDAC 67707
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_CommandText),
        ]
        override public string CommandText {
            get {
                string value = _commandText;
                return ((null != value) ? value : ADP.StrEmpty);
            }
            set {
                if (Bid.TraceOn) {
                    Bid.Trace("<oledb.OleDbCommand.set_CommandText|API> %d#, '", ObjectID);
                    Bid.PutStr(value); // Use PutStr to write out entire string
                    Bid.Trace("'\n");
                }
                if (0 != ADP.SrcCompare(_commandText, value)) {
                    PropertyChanging();
                    _commandText = value;
                }
            }
        }

        [
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_CommandTimeout),
        ]
        override public int CommandTimeout { // V1.2.3300, XXXCommand V1.0.5000
            get {
                return _commandTimeout;
            }
            set {
                Bid.Trace("<oledb.OleDbCommand.set_CommandTimeout|API> %d#, %d\n", ObjectID, value);
                if (value < 0) {
                    throw ADP.InvalidCommandTimeout(value);
                }
                if (value != _commandTimeout) {
                    PropertyChanging();
                    _commandTimeout = value;
                }
            }
        }

        public void ResetCommandTimeout() { // V1.2.3300
            if (ADP.DefaultCommandTimeout != _commandTimeout) {
                PropertyChanging();
                _commandTimeout = ADP.DefaultCommandTimeout;
            }
        }

        private bool ShouldSerializeCommandTimeout() { // V1.2.3300
            return (ADP.DefaultCommandTimeout != _commandTimeout);
        }

        [
        DefaultValue(System.Data.CommandType.Text),
        RefreshProperties(RefreshProperties.All),
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_CommandType),
        ]
        override public CommandType CommandType {
            get {
                CommandType cmdType = _commandType;
                return ((0 != cmdType) ? cmdType : CommandType.Text);
            }
            set  {
                switch(value) { // @perfnote: Enum.IsDefined
                case CommandType.Text:
                case CommandType.StoredProcedure:
                case CommandType.TableDirect:
                    PropertyChanging();
                    _commandType = value;
                    break;
                default:
                    throw ADP.InvalidCommandType(value);
                }
            }
        }

        [
        DefaultValue(null),
        Editor("Microsoft.VSDesigner.Data.Design.DbConnectionEditor, " + AssemblyRef.MicrosoftVSDesigner, "System.Drawing.Design.UITypeEditor, " + AssemblyRef.SystemDrawing),
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_Connection),
        ]
        new public OleDbConnection Connection {
            get {
                return _connection;
            }
            set {
                OleDbConnection connection = _connection;
                if (value != connection) {
                    PropertyChanging();
                    ResetConnection();

                    _connection = value;
                    Bid.Trace("<oledb.OleDbCommand.set_Connection|API> %d#\n", ObjectID);

                    if (null != value) {
                        _transaction = OleDbTransaction.TransactionUpdate(_transaction); // MDAC 63226
                    }
                }
            }
        }

        private void ResetConnection() {
            OleDbConnection connection = _connection;
            if (null != connection) {
                PropertyChanging();
                CloseInternal();
                if (_trackingForClose) {
                    connection.RemoveWeakReference(this);
                    _trackingForClose = false;
                }
            }
            _connection = null;
        }

        override protected DbConnection DbConnection { // V1.2.3300
            get {
                return Connection;
            }
            set {
                Connection = (OleDbConnection)value;
            }
        }

        override protected DbParameterCollection DbParameterCollection { // V1.2.3300
            get {
                return Parameters;
            }
        }

        override protected DbTransaction DbTransaction { // V1.2.3300
            get {
                return Transaction;
            }
            set {
                Transaction = (OleDbTransaction)value;
            }
        }

        // @devnote: By default, the cmd object is visible on the design surface (i.e. VS7 Server Tray)
        // to limit the number of components that clutter the design surface,
        // when the DataAdapter design wizard generates the insert/update/delete commands it will
        // set the DesignTimeVisible property to false so that cmds won't appear as individual objects
        [
        DefaultValue(true),
        DesignOnly(true),
        Browsable(false),
        EditorBrowsableAttribute(EditorBrowsableState.Never),
        ]
        public override bool DesignTimeVisible { // V1.2.3300, XXXCommand V1.0.5000
            get {
                return !_designTimeInvisible;
            }
            set {
                _designTimeInvisible = !value;
                TypeDescriptor.Refresh(this); // VS7 208845
            }
        }

        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Content),
        ResCategoryAttribute(Res.DataCategory_Data),
        ResDescriptionAttribute(Res.DbCommand_Parameters),
        ]
        new public OleDbParameterCollection Parameters {
            get {
                OleDbParameterCollection value = _parameters;
                if (null == value) {
                    // delay the creation of the OleDbParameterCollection
                    // until user actually uses the Parameters property
                    value = new OleDbParameterCollection();
                    _parameters = value;
                }
                return value;
            }
        }

        private bool HasParameters() { // MDAC 65548
            OleDbParameterCollection value = _parameters;
            return (null != value) && (0 < value.Count); // VS 300569
        }

        [
        Browsable(false),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        ResDescriptionAttribute(Res.DbCommand_Transaction),
        ]
        new public OleDbTransaction Transaction {
            get {
                // find the last non-zombied local transaction object, but not transactions
                // that may have been started after the current local transaction
                OleDbTransaction transaction = _transaction;
                while ((null != transaction) && (null == transaction.Connection)) {
                    transaction = transaction.Parent;
                    _transaction = transaction;
                }
                return transaction;
            }
            set {
                _transaction = value;
                Bid.Trace("<oledb.OleDbCommand.set_Transaction|API> %d#\n", ObjectID);
            }
        }

        [
        DefaultValue(System.Data.UpdateRowSource.Both),
        ResCategoryAttribute(Res.DataCategory_Update),
        ResDescriptionAttribute(Res.DbCommand_UpdatedRowSource),
        ]
        override public UpdateRowSource UpdatedRowSource { // V1.2.3300, XXXCommand V1.0.5000
            get {
                return _updatedRowSource;
            }
            set {
                switch(value) { // @perfnote: Enum.IsDefined
                case UpdateRowSource.None:
                case UpdateRowSource.OutputParameters:
                case UpdateRowSource.FirstReturnedRecord:
                case UpdateRowSource.Both:
                    _updatedRowSource = value;
                    break;
                default:
                    throw ADP.InvalidUpdateRowSource(value);
                }
            }
        }

        // required interface, safe cast
        private UnsafeNativeMethods.IAccessor IAccessor() {
            Bid.Trace("<oledb.IUnknown.QueryInterface|API|OLEDB|command> %d#, IAccessor\n", ObjectID);
            Debug.Assert(null != _icommandText, "IAccessor: null ICommandText");
            return (UnsafeNativeMethods.IAccessor) _icommandText;
        }

        // required interface, safe cast
        internal UnsafeNativeMethods.ICommandProperties ICommandProperties() {
            Bid.Trace("<oledb.IUnknown.QueryInterface|API|OLEDB|command> %d#, ICommandProperties\n", ObjectID);
            Debug.Assert(null != _icommandText, "ICommandProperties: null ICommandText");
            return (UnsafeNativeMethods.ICommandProperties) _icommandText;
        }

        // optional interface, unsafe cast
        private UnsafeNativeMethods.ICommandPrepare ICommandPrepare() {
            Bid.Trace("<oledb.IUnknown.QueryInterface|API|OLEDB|command> %d#, ICommandPrepare\n", ObjectID);
            Debug.Assert(null != _icommandText, "ICommandPrepare: null ICommandText");
            return (_icommandText as UnsafeNativeMethods.ICommandPrepare);
        }

        // optional interface, unsafe cast
        private UnsafeNativeMethods.ICommandWithParameters ICommandWithParameters() {
            Bid.Trace("<oledb.IUnknown.QueryInterface|API|OLEDB|command> %d#, ICommandWithParameters\n", ObjectID);
            Debug.Assert(null != _icommandText, "ICommandWithParameters: null ICommandText");
            UnsafeNativeMethods.ICommandWithParameters value = (_icommandText as UnsafeNativeMethods.ICommandWithParameters);
            if (null == value) {
                throw ODB.NoProviderSupportForParameters(_connection.Provider, (Exception)null);
            }
            return value;
        }

        private void CreateAccessor() {
            Debug.Assert(System.Data.CommandType.Text == CommandType || System.Data.CommandType.StoredProcedure == CommandType, "CreateAccessor: incorrect CommandType");
            Debug.Assert(null == _dbBindings, "CreateAccessor: already has dbBindings");
            Debug.Assert(HasParameters(), "CreateAccessor: unexpected, no parameter collection");

            // do this first in-case the command doesn't support parameters
            UnsafeNativeMethods.ICommandWithParameters commandWithParameters = ICommandWithParameters();

            OleDbParameterCollection collection = _parameters;
            OleDbParameter[] parameters = new OleDbParameter[collection.Count];
            collection.CopyTo(parameters, 0);

            // _dbBindings is used as a switch during ExecuteCommand, so don't set it until everything okay
            Bindings bindings = new Bindings(parameters, collection.ChangeID);

            for (int i = 0; i < parameters.Length; ++i) {
                bindings.ForceRebind |= parameters[i].BindParameter(i, bindings);
            }

            bindings.AllocateForAccessor(null, 0, 0);

            ApplyParameterBindings(commandWithParameters, bindings.BindInfo);

            UnsafeNativeMethods.IAccessor iaccessor = IAccessor();
            OleDbHResult hr = bindings.CreateAccessor(iaccessor, ODB.DBACCESSOR_PARAMETERDATA);
            if (hr < 0) {
                ProcessResults(hr);
            }
            _dbBindings = bindings;
        }

        private void ApplyParameterBindings(UnsafeNativeMethods.ICommandWithParameters commandWithParameters, tagDBPARAMBINDINFO[] bindInfo) {
            IntPtr[] ordinals = new IntPtr[bindInfo.Length];
            for (int i = 0; i < ordinals.Length; ++i) {
                ordinals[i] = (IntPtr)(i+1);
            }

            Bid.Trace("<oledb.ICommandWithParameters.SetParameterInfo|API|OLEDB> %d#\n", ObjectID);
            OleDbHResult hr = commandWithParameters.SetParameterInfo((IntPtr)bindInfo.Length, ordinals, bindInfo);
            Bid.Trace("<oledb.ICommandWithParameters.SetParameterInfo|API|OLEDB|RET> %08X{HRESULT}\n", hr);

            if (hr < 0) {
                ProcessResults(hr);
            }
        }

        override public void Cancel() {
            IntPtr hscp;
            Bid.ScopeEnter(out hscp, "<oledb.OleDbCommand.Cancel|API> %d#\n", ObjectID);
            try {
                unchecked { _changeID++; }

                UnsafeNativeMethods.ICommandText icmdtxt = _icommandText;
                if (null != icmdtxt) {
                    OleDbHResult hr = OleDbHResult.S_OK;

                    lock(icmdtxt) {
                        // lock the object to avoid race conditions between using the object and releasing the object
                        // after we acquire the lock, if the class has moved on don't actually call Cancel
                        if (icmdtxt == _icommandText) {
                            Bid.Trace("<oledb.ICommandText.Cancel|API|OLEDB> %d#\n", ObjectID);
                            hr = icmdtxt.Cancel();
                            Bid.Trace("<oledb.ICommandText.Cancel|API|OLEDB|RET> %08X{HRESULT}\n", hr);
                        }
                    }
                    if (OleDbHResult.DB_E_CANTCANCEL != hr) {
                        // if the provider can't cancel the command - don't cancel the DataReader
                        this.canceling = true;
                    }

                    // since cancel is allowed to occur at anytime we can't check the connection status
                    // since if it returns as closed then the connection will close causing the reader to close
                    // and that would introduce the possilbility of one thread reading and one thread closing at the same time
                    ProcessResultsNoReset(hr); // MDAC 72667
                }
                else {
                    this.canceling = true;
                }
            }
            finally {
                Bid.ScopeLeave(ref hscp);
            }
        }

        public OleDbCommand Clone() {
            OleDbCommand clone = new OleDbCommand(this);
            Bid.Trace("<oledb.OleDbCommand.Clone|API> %d#, clone=%d#\n", ObjectID, clone.ObjectID);
            return clone;
        }

        object ICloneable.Clone() {
            return Clone();
        }

        // Connection.Close & Connection.Dispose(true) notification
        internal void CloseCommandFromConnection(bool canceling) {
            this.canceling = canceling; // MDAC 71435
            CloseInternal();
            _trackingForClose = false;
            _transaction = null;
            //GC.SuppressFinalize(this);
        }

        internal void CloseInternal() {
            Debug.Assert(null != _connection, "no connection, CloseInternal");
            CloseInternalParameters();
            CloseInternalCommand();
        }

        // may be called from either
        //      OleDbDataReader.Close/Dispose
        //      via OleDbCommand.Dispose or OleDbConnection.Close
        internal void CloseFromDataReader(Bindings bindings) {
            if (null != bindings) {
                if (canceling) {
                    bindings.Dispose();
                    Debug.Assert(_dbBindings == bindings, "bindings with two owners");
                }
                else {
                    bindings.ApplyOutputParameters();
                    ParameterBindings = bindings;
                }
            }
            _hasDataReader = false;
        }

        private void CloseInternalCommand() {
            unchecked { _changeID++; }
            this.commandBehavior = CommandBehavior.Default;
            _isPrepared = false;

            

            UnsafeNativeMethods.ICommandText ict = Interlocked.Exchange<UnsafeNativeMethods.ICommandText>(ref _icommandText, null);
            if (null != ict) {
                lock(ict) {
                    // lock the object to avoid race conditions between using the object and releasing the object
                    Marshal.ReleaseComObject(ict);
                }
            }
        }
        private void CloseInternalParameters() {
            Debug.Assert(null != _connection, "no connection, CloseInternalParameters");
            Bindings bindings = _dbBindings;
            _dbBindings = null;
            if (null != bindings) {
                bindings.Dispose();
            }
        }

        new public OleDbParameter CreateParameter() {
            return new OleDbParameter();
        }

        override protected DbParameter CreateDbParameter() {
            return CreateParameter();
        }

        override protected void Dispose(bool disposing) { // MDAC 65459
            if (disposing) { // release mananged objects
                // the DataReader takes ownership of the parameter Bindings
                // this way they don't get destroyed when user calls OleDbCommand.Dispose
                // when there is an open DataReader

                unchecked { _changeID++; }

                // in V1.0, V1.1 the Connection,Parameters,CommandText,Transaction where reset
                ResetConnection();
                _transaction = null;
                _parameters = null;
                CommandText = null;
            }
            // release unmanaged objects
            base.Dispose(disposing); // notify base classes
        }


        new public OleDbDataReader ExecuteReader() {
            return ExecuteReader(CommandBehavior.Default);
        }

        IDataReader IDbCommand.ExecuteReader() {
            return ExecuteReader(CommandBehavior.Default);
        }

        new public OleDbDataReader ExecuteReader(CommandBehavior behavior) {
            OleDbConnection.ExecutePermission.Demand();

            IntPtr hscp;
            Bid.ScopeEnter(out hscp, "<oledb.OleDbCommand.ExecuteReader|API> %d#, behavior=%d{ds.CommandBehavior}\n", ObjectID, (int)behavior);
            try {
                _executeQuery = true;
                return ExecuteReaderInternal(behavior, ADP.ExecuteReader);
            }
            finally {
                Bid.ScopeLeave(ref hscp);
            }
        }

        IDataReader IDbCommand.ExecuteReader(CommandBehavior behavior) {
            return ExecuteReader(behavior);
        }

        override protected DbDataReader ExecuteDbDataReader(CommandBehavior behavior) {
            return ExecuteReader(behavior);
        }

        private OleDbDataReader ExecuteReaderInternal(CommandBehavior behavior, string method) {
            OleDbDataReader dataReader = null;
            OleDbException nextResultsFailure = null;
            int state = ODB.InternalStateClosed;
            try {
                ValidateConnectionAndTransaction(method);

                if (0 != (CommandBehavior.SingleRow & behavior)) {
                    // CommandBehavior.SingleRow implies CommandBehavior.SingleResult
                    behavior |= CommandBehavior.SingleResult;
                }

                object executeResult;
                int resultType;

                switch(CommandType) {
                case 0: // uninitialized CommandType.Text
                case CommandType.Text:
                case CommandType.StoredProcedure:
                    resultType = ExecuteCommand(behavior, out executeResult);
                    break;

                case CommandType.TableDirect:
                    resultType = ExecuteTableDirect(behavior, out executeResult);
                    break;

                default:
                    throw ADP.InvalidCommandType(CommandType);
                }

                if (_executeQuery) {
                    try {
                        dataReader = new OleDbDataReader(_connection, this, 0, this.commandBehavior);

                        switch(resultType) {
                        case ODB.ExecutedIMultipleResults:
                            dataReader.InitializeIMultipleResults(executeResult);
                            dataReader.NextResult();
                            break;
                        case ODB.ExecutedIRowset:
                            dataReader.InitializeIRowset(executeResult, ChapterHandle.DB_NULL_HCHAPTER, _recordsAffected);
                            dataReader.BuildMetaInfo();
                            dataReader.HasRowsRead();
                            break;
                        case ODB.ExecutedIRow:
                            dataReader.InitializeIRow(executeResult, _recordsAffected);
                            dataReader.BuildMetaInfo();
                            break;
                        case ODB.PrepareICommandText:
                            if (!_isPrepared) {
                                PrepareCommandText(2);
                            }
                            OleDbDataReader.GenerateSchemaTable(dataReader, _icommandText, behavior);
                            break;
                        default:
                            Debug.Assert(false, "ExecuteReaderInternal: unknown result type");
                            break;
                        }
                        executeResult = null;
                        _hasDataReader = true;
                        _connection.AddWeakReference(dataReader, OleDbReferenceCollection.DataReaderTag);

                        // command stays in the executing state until the connection
                        // has a datareader to track for it being closed
                        state = ODB.InternalStateOpen; // MDAC 72655
                    }
                    finally {
                        if (ODB.InternalStateOpen != state) {
                            this.canceling = true;
                            if (null != dataReader) {
                                ((IDisposable) dataReader).Dispose();
                                dataReader = null;
                            }
                        }
                    }
                    Debug.Assert(null != dataReader, "ExecuteReader should never return a null DataReader");
                }
                else { // optimized code path for ExecuteNonQuery to not create a OleDbDataReader object
                    try {
                        if (ODB.ExecutedIMultipleResults == resultType) {
                            UnsafeNativeMethods.IMultipleResults multipleResults = (UnsafeNativeMethods.IMultipleResults) executeResult;

                            // may cause a Connection.ResetState which closes connection
                            nextResultsFailure = OleDbDataReader.NextResults(multipleResults, _connection, this, out _recordsAffected);
                        }
                    }
                    finally {
                        try {
                            if (null != executeResult) {
                                Marshal.ReleaseComObject(executeResult);
                                executeResult = null;
                            }
                            CloseFromDataReader(ParameterBindings);
                        }
                        catch(Exception e) {
                            // 
                            if (!ADP.IsCatchableExceptionType(e)) {
                                throw;
                            }
                            if (null != nextResultsFailure) {
                                nextResultsFailure = new OleDbException(nextResultsFailure, e);
                            }
                            else {
                                throw;
                            }
                        }
                    }
                }
            }
            finally { // finally clear executing state
                try {
                    if ((null == dataReader) && (ODB.InternalStateOpen != state)) { // MDAC 67218
                        ParameterCleanup();
                    }
                }
                catch(Exception e) {
                    // 
                    if (!ADP.IsCatchableExceptionType(e)) {
                        throw;
                    }
                    if (null != nextResultsFailure) {
                        nextResultsFailure = new OleDbException(nextResultsFailure, e);
                    }
                    else {
                        throw;
                    }
                }
                if (null != nextResultsFailure) {
                    throw nextResultsFailure;
                }
            }
            return dataReader;
        }

        private int ExecuteCommand(CommandBehavior behavior, out object executeResult) {
            if (InitializeCommand(behavior, false)) {
                if (0 != (CommandBehavior.SchemaOnly & this.commandBehavior)) {
                    executeResult = null;
                    return ODB.PrepareICommandText;
                }
                return ExecuteCommandText(out executeResult);
            }
            return ExecuteTableDirect(behavior, out executeResult); // MDAC 57856
        }

        // dbindings handle can't be freed until the output parameters
        // have been filled in which occurs after the last rowset is released
        // dbbindings.FreeDataHandle occurs in Cloe
        private int ExecuteCommandText(out object executeResult) {
            int retcode;
            tagDBPARAMS dbParams = null;
            RowBinding rowbinding = null;
            Bindings bindings = ParameterBindings;
            bool mustRelease = false;

            RuntimeHelpers.PrepareConstrainedRegions();
            try {
                if (null != bindings) { // parameters may be suppressed
                    rowbinding = bindings.RowBinding();

                    rowbinding.DangerousAddRef(ref mustRelease);

                    // bindings can't be released until after last rowset is released
                    // that is when output parameters are populated
                    // initialize the input parameters to the input databuffer
                    bindings.ApplyInputParameters();

                    dbParams = new tagDBPARAMS();
                    dbParams.pData = rowbinding.DangerousGetDataPtr();
                    dbParams.cParamSets = 1;
                    dbParams.hAccessor = rowbinding.DangerousGetAccessorHandle();
                }
                if ((0 == (CommandBehavior.SingleResult & this.commandBehavior)) && _connection.SupportMultipleResults()) {
                    retcode = ExecuteCommandTextForMultpleResults(dbParams, out executeResult);
                }
                else if (0 == (CommandBehavior.SingleRow & this.commandBehavior) || !_executeQuery) {
                    retcode = ExecuteCommandTextForSingleResult(dbParams, out executeResult);
                }
                else {
                    retcode = ExecuteCommandTextForSingleRow(dbParams, out executeResult);
                }
            }
            finally {
                if (mustRelease) {
                    rowbinding.DangerousRelease();
                }
            }
            return retcode;
        }

        private int ExecuteCommandTextForMultpleResults(tagDBPARAMS dbParams, out object executeResult) {
            Debug.Assert(0 == (CommandBehavior.SingleRow & this.commandBehavior), "SingleRow implies SingleResult");
            OleDbHResult hr;

            Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB> %d#, IID_IMultipleResults\n", ObjectID);
            hr = _icommandText.Execute(ADP.PtrZero, ref ODB.IID_IMultipleResults, dbParams, out _recordsAffected, out executeResult);
            Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB|RET> %08X{HRESULT}, RecordsAffected=%Id\n", hr, _recordsAffected);

            if (OleDbHResult.E_NOINTERFACE != hr) {
                ExecuteCommandTextErrorHandling(hr);
                return ODB.ExecutedIMultipleResults;
            }
            SafeNativeMethods.Wrapper.ClearErrorInfo();
            return ExecuteCommandTextForSingleResult(dbParams, out executeResult);
        }

        private int ExecuteCommandTextForSingleResult(tagDBPARAMS dbParams, out object executeResult) {
            OleDbHResult hr;

            // MDAC 64465 (Microsoft.Jet.OLEDB.4.0 returns 0 for recordsAffected instead of -1)
            if (_executeQuery) {
                Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB> %d#, IID_IRowset\n", ObjectID);
                hr = _icommandText.Execute(ADP.PtrZero, ref ODB.IID_IRowset, dbParams, out _recordsAffected, out executeResult);
                Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB|RET> %08X{HRESULT}, RecordsAffected=%Id\n", hr, _recordsAffected);
            }
            else {
                Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB> %d#, IID_NULL\n", ObjectID);
                hr = _icommandText.Execute(ADP.PtrZero, ref ODB.IID_NULL, dbParams, out _recordsAffected, out executeResult);
                Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB|RET> %08X{HRESULT}, RecordsAffected=%Id\n", hr, _recordsAffected);
            }
            ExecuteCommandTextErrorHandling(hr);
            return ODB.ExecutedIRowset;
        }

        private int ExecuteCommandTextForSingleRow(tagDBPARAMS dbParams, out object executeResult) {
            Debug.Assert(_executeQuery, "ExecuteNonQuery should always use ExecuteCommandTextForSingleResult");

            if (_connection.SupportIRow(this)) {
                OleDbHResult hr;

                Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB> %d#, IID_IRow\n", ObjectID);
                hr = _icommandText.Execute(ADP.PtrZero, ref ODB.IID_IRow, dbParams, out _recordsAffected, out executeResult);
                Bid.Trace("<oledb.ICommandText.Execute|API|OLEDB|RET> %08X{HRESULT}, RecordsAffected=%Id\n", hr, _recordsAffected);

                if (OleDbHResult.DB_E_NOTFOUND == hr) { // MDAC 76110
                    SafeNativeMethods.Wrapper.ClearErrorInfo();
                    return ODB.ExecutedIRow;
                }
                else if (OleDbHResult.E_NOINTERFACE != hr) {
                    ExecuteCommandTextErrorHandling(hr);
                    return ODB.ExecutedIRow;
                }
            }
            SafeNativeMethods.Wrapper.ClearErrorInfo();
            return ExecuteCommandTextForSingleResult(dbParams, out executeResult);
        }

        private void ExecuteCommandTextErrorHandling(OleDbHResult hr) {
            Exception e = OleDbConnection.ProcessResults(hr, _connection, this);
            if (null != e) {
                e = ExecuteCommandTextSpecialErrorHandling(hr, e);
                throw e;
            }
        }

        private Exception ExecuteCommandTextSpecialErrorHandling(OleDbHResult hr, Exception e) {
            if (((OleDbHResult.DB_E_ERRORSOCCURRED == hr) || (OleDbHResult.DB_E_BADBINDINFO == hr)) && (null != _dbBindings)) { // MDAC 66026, 67039
                //
                // this code exist to try for a better user error message by post-morten detection
                // of invalid parameter types being passed to a provider that doesn't understand
                // the user specified parameter OleDbType

                Debug.Assert(null != e, "missing inner exception");

                StringBuilder builder = new StringBuilder();
                ParameterBindings.ParameterStatus(builder);
                e = ODB.CommandParameterStatus(builder.ToString(), e);
            }
            return e;
        }

        override public int ExecuteNonQuery() {
            OleDbConnection.ExecutePermission.Demand();

            IntPtr hscp;
            Bid.ScopeEnter(out hscp, "<oledb.OleDbCommand.ExecuteNonQuery|API> %d#\n", ObjectID);
            try {
                _executeQuery = false;
                ExecuteReaderInternal(CommandBehavior.Default, ADP.ExecuteNonQuery);
                return ADP.IntPtrToInt32(_recordsAffected);
            }
            finally {
                Bid.ScopeLeave(ref hscp);
            }
        }

        override public object ExecuteScalar() {
            OleDbConnection.ExecutePermission.Demand();

            IntPtr hscp;
            Bid.ScopeEnter(out hscp, "<oledb.OleDbCommand.ExecuteScalar|API> %d#\n", ObjectID);
            try {
                object value = null;
                _executeQuery = true;
                using(OleDbDataReader reader = ExecuteReaderInternal(CommandBehavior.Default, ADP.ExecuteScalar)) {
                    if (reader.Read() && (0 < reader.FieldCount)) {
                        value = reader.GetValue(0);
                    }
                }
                return value;
            }
            finally {
                Bid.ScopeLeave(ref hscp);
            }
        }

        private int ExecuteTableDirect(CommandBehavior behavior, out object executeResult) {
            this.commandBehavior = behavior;
            executeResult = null;

            OleDbHResult hr = OleDbHResult.S_OK;
            
            StringMemHandle sptr = null;
            bool            mustReleaseStringHandle = false;

            RuntimeHelpers.PrepareConstrainedRegions();
            try {
                sptr = new StringMemHandle(ExpandCommandText());

                sptr.DangerousAddRef(ref mustReleaseStringHandle);

                if (mustReleaseStringHandle) {
                    tagDBID tableID = new tagDBID();
                    tableID.uGuid = Guid.Empty;
                    tableID.eKind = ODB.DBKIND_NAME;
                    tableID.ulPropid = sptr.DangerousGetHandle();

                    using(IOpenRowsetWrapper iopenRowset = _connection.IOpenRowset()) {
                        using(DBPropSet propSet = CommandPropertySets()) {
                            if (null != propSet) {

                                // MDAC 65279
                                Bid.Trace("<oledb.IOpenRowset.OpenRowset|API|OLEDB> %d#, IID_IRowset\n", ObjectID);
                                bool mustRelease = false;
                                RuntimeHelpers.PrepareConstrainedRegions();
                                try {
                                    propSet.DangerousAddRef(ref mustRelease);
                                    hr = iopenRowset.Value.OpenRowset(ADP.PtrZero, tableID, ADP.PtrZero, ref ODB.IID_IRowset, propSet.PropertySetCount, propSet.DangerousGetHandle(), out executeResult);
                                }
                                finally {
                                    if (mustRelease) {
                                        propSet.DangerousRelease();
                                    }
                                }
                                    
                                Bid.Trace("<oledb.IOpenRowset.OpenRowset|API|OLEDB|RET> %08X{HRESULT}", hr);

                                if (OleDbHResult.DB_E_ERRORSOCCURRED == hr) {
                                    Bid.Trace("<oledb.IOpenRowset.OpenRowset|API|OLEDB> %d#, IID_IRowset\n", ObjectID);
                                    hr = iopenRowset.Value.OpenRowset(ADP.PtrZero, tableID, ADP.PtrZero, ref ODB.IID_IRowset, 0, IntPtr.Zero, out executeResult);
                                    Bid.Trace("<oledb.IOpenRowset.OpenRowset|API|OLEDB|RET> %08X{HRESULT}", hr);
                                }
                            }
                            else {
                                Bid.Trace("<oledb.IOpenRowset.OpenRowset|API|OLEDB> %d#, IID_IRowset\n", ObjectID);
                                hr = iopenRowset.Value.OpenRowset(ADP.PtrZero, tableID, ADP.PtrZero, ref ODB.IID_IRowset, 0, IntPtr.Zero, out executeResult);
                                Bid.Trace("<oledb.IOpenRowset.OpenRowset|API|OLEDB|RET> %08X{HRESULT}", hr);
                            }
                        }
                    }
                }
            }
            finally {
                if (mustReleaseStringHandle) {
                    sptr.DangerousRelease();
                }
            }
            ProcessResults(hr);
            _recordsAffected = ADP.RecordsUnaffected;
            return ODB.ExecutedIRowset;
        }

        private string ExpandCommandText() {
            string cmdtxt = CommandText;
            if (ADP.IsEmpty(cmdtxt)) {
                return ADP.StrEmpty;
            }
            CommandType cmdtype = CommandType;
            switch(cmdtype) {
            case System.Data.CommandType.Text:
                // do nothing, already expanded by user
                return cmdtxt;

            case System.Data.CommandType.StoredProcedure:
                // { ? = CALL SPROC (? ?) }, { ? = CALL SPROC }, { CALL SPRC (? ?) }, { CALL SPROC }
                return ExpandStoredProcedureToText(cmdtxt);

            case System.Data.CommandType.TableDirect:
                // @devnote: Provider=Jolt4.0 doesn't like quoted table names, SQOLEDB requires them
                // Providers should not require table names to be quoted and should guarantee that
                // unquoted table names correctly open the specified table, even if the table name
                // contains special characters, as long as the table can be unambiguously identified
                // without quoting.
                return cmdtxt;

            default:
                throw ADP.InvalidCommandType(cmdtype);
            }
        }

        private string ExpandOdbcMaximumToText(string sproctext, int parameterCount) {
            StringBuilder builder = new StringBuilder();
            if ((0 < parameterCount) && (ParameterDirection.ReturnValue == Parameters[0].Direction)) {
                parameterCount--;
                builder.Append("{ ? = CALL ");
            }
            else {
                builder.Append("{ CALL ");
            }
            builder.Append(sproctext); // WebData 95634

            switch(parameterCount) {
            case 0:
                builder.Append(" }");
                break;
            case 1:
                builder.Append("( ? ) }");
                break;
            default:
                builder.Append("( ?, ?");
                for (int i = 2; i < parameterCount; ++i) {
                    builder.Append(", ?");
                }
                builder.Append(" ) }");
                break;
            }
            return builder.ToString();
        }

        private string ExpandOdbcMinimumToText(string sproctext, int parameterCount) {
            //if ((0 < parameterCount) && (ParameterDirection.ReturnValue == Parameters[0].Direction)) {
            //    Debug.Assert("doesn't support ReturnValue parameters");
            //}
            StringBuilder builder = new StringBuilder();
            builder.Append("exec ");
            builder.Append(sproctext);
            if (0 < parameterCount) {
                builder.Append(" ?");
                for(int i = 1; i < parameterCount; ++i) {
                    builder.Append(", ?");
                }
            }
            return builder.ToString();
        }

        private string ExpandStoredProcedureToText(string sproctext) {
            Debug.Assert(null != _connection, "ExpandStoredProcedureToText: null Connection");

            int parameterCount = (null != _parameters) ? _parameters.Count : 0;
            if (0 == (ODB.DBPROPVAL_SQL_ODBC_MINIMUM & _connection.SqlSupport())) {
                return ExpandOdbcMinimumToText(sproctext, parameterCount);
            }
            return ExpandOdbcMaximumToText(sproctext, parameterCount);
        }

        private void ParameterCleanup() {
            Bindings bindings = ParameterBindings;
            if (null != bindings) {
                bindings.CleanupBindings();
            }
        }

        private bool InitializeCommand(CommandBehavior behavior, bool throwifnotsupported) {
            Debug.Assert(null != _connection, "InitializeCommand: null OleDbConnection");

            int changeid = _changeID;
            if ((0 != (CommandBehavior.KeyInfo & (this.commandBehavior ^ behavior))) || (_lastChangeID != changeid)) {
                CloseInternalParameters(); // could optimize out
                CloseInternalCommand();
            }
            this.commandBehavior = behavior;
            changeid = _changeID;

            if (!PropertiesOnCommand(false)) {
                return false; // MDAC 57856
            }

            if ((null != _dbBindings) && _dbBindings.AreParameterBindingsInvalid(_parameters)) {
                CloseInternalParameters();
            }

            // if we already having bindings - don't create the accessor
            // if _parameters is null - no parameters exist - don't create the collection
            // do we actually have parameters since the collection exists
            if ((null == _dbBindings) && HasParameters()) {
                // if we setup the parameters before setting cmdtxt then named parameters can happen
                CreateAccessor();
            }

            if (_lastChangeID != changeid) {
                OleDbHResult hr;

                String commandText = ExpandCommandText();

                if (Bid.TraceOn) {
                    Bid.Trace("<oledb.ICommandText.SetCommandText|API|OLEDB> %d#, DBGUID_DEFAULT, CommandText='", ObjectID);
                    Bid.PutStr(commandText); // Use PutStr to write out entire string
                    Bid.Trace("'\n");
                }
                hr = _icommandText.SetCommandText(ref ODB.DBGUID_DEFAULT, commandText);
                Bid.Trace("<oledb.ICommandText.SetCommandText|API|OLEDB|RET> %08X{HRESULT}\n", hr);

                if (hr < 0) {
                    ProcessResults(hr);
                }
            }

            _lastChangeID = changeid;

            return true;
        }

        private void PropertyChanging() {
            unchecked { _changeID++; }
        }

        override public void Prepare() {
            OleDbConnection.ExecutePermission.Demand();

            IntPtr hscp;
            Bid.ScopeEnter(out hscp, "<oledb.OleDbCommand.Prepare|API> %d#\n", ObjectID);
            try {
                if (CommandType.TableDirect != CommandType) { // MDAC 70946, 71194
                    ValidateConnectionAndTransaction(ADP.Prepare);

                    _isPrepared = false;
                    if (CommandType.TableDirect != CommandType) {
                        InitializeCommand(0, true);
                        PrepareCommandText(1);
                    }
                }
            }
            finally {
                Bid.ScopeLeave(ref hscp);
            }
        }

        private void PrepareCommandText(int expectedExecutionCount) {
            OleDbParameterCollection parameters = _parameters;
            if (null != parameters) {
                foreach(OleDbParameter parameter in parameters) {
                    if (parameter.IsParameterComputed()) {
                        // @devnote: use IsParameterComputed which is called in the normal case
                        // only to call Prepare to throw the specialized error message
                        // reducing the overall number of methods to actually jit
                        parameter.Prepare(this); // MDAC 70232
                    }
                }
            }
            UnsafeNativeMethods.ICommandPrepare icommandPrepare = ICommandPrepare();
            if (null != icommandPrepare) {
                OleDbHResult hr;

                Bid.Trace("<oledb.ICommandPrepare.Prepare|API|OLEDB> %d#, expectedExecutionCount=%d\n", ObjectID, expectedExecutionCount);
                hr = icommandPrepare.Prepare(expectedExecutionCount);
                Bid.Trace("<oledb.ICommandPrepare.Prepare|API|OLEDB|RET> %08X{HRESULT}\n", hr);

                ProcessResults(hr);

            }
            // don't recompute bindings on prepared statements
            _isPrepared = true;
        }

        private void ProcessResults(OleDbHResult hr) {
            Exception e = OleDbConnection.ProcessResults(hr, _connection, this);
            if (null != e) { throw e; }
        }

        private void ProcessResultsNoReset(OleDbHResult hr) {
            Exception e = OleDbConnection.ProcessResults(hr, null, this);
            if (null != e) { throw e; }
        }

        internal object GetPropertyValue(Guid propertySet, int propertyID) {
            if (null != _icommandText) {
                OleDbHResult hr;
                tagDBPROP[] dbprops;
                UnsafeNativeMethods.ICommandProperties icommandProperties = ICommandProperties();

                using(PropertyIDSet propidset = new PropertyIDSet(propertySet, propertyID)) {

                    using(DBPropSet propset = new DBPropSet(icommandProperties, propidset, out hr)) {
                        if (hr < 0) {
                            // VSDD 621427: OLEDB Data Reader masks provider specific errors by raising "Internal .Net Framework Data Provider error 30."
                            // DBPropSet c-tor will register the exception and it will be raised at GetPropertySet call in case of failure
                            SafeNativeMethods.Wrapper.ClearErrorInfo();
                        }
                        dbprops = propset.GetPropertySet(0, out propertySet);
                    }
                }
                if (OleDbPropertyStatus.Ok == dbprops[0].dwStatus) {
                    return dbprops[0].vValue;
                }
                return dbprops[0].dwStatus;
            }
            return OleDbPropertyStatus.NotSupported;
        }

        private bool PropertiesOnCommand(bool throwNotSupported) {
            if (null != _icommandText) {
                return true;
            }
            Debug.Assert(!_isPrepared, "null command isPrepared");

            OleDbConnection connection = _connection;
            if (null == connection) {
                connection.CheckStateOpen(ODB.Properties);
            }
            if (!_trackingForClose) {
                _trackingForClose = true;
                connection.AddWeakReference(this, OleDbReferenceCollection.CommandTag);
            }
            _icommandText = connection.ICommandText();

            if (null == _icommandText) {
                if (throwNotSupported || HasParameters()) {
                    throw ODB.CommandTextNotSupported(connection.Provider, null);
                }
                return false; // MDAC 57856
            }

            using(DBPropSet propSet = CommandPropertySets()) {
                if (null != propSet) {
                    UnsafeNativeMethods.ICommandProperties icommandProperties = ICommandProperties();

                    Bid.Trace("<oledb.ICommandProperties.SetProperties|API|OLEDB> %d#\n", ObjectID);
                    OleDbHResult hr = icommandProperties.SetProperties(propSet.PropertySetCount, propSet);
                    Bid.Trace("<oledb.ICommandProperties.SetProperties|API|OLEDB|RET> %08X{HRESULT}\n", hr);

                    if (hr < 0) {
                        SafeNativeMethods.Wrapper.ClearErrorInfo();
                    }
                }
            }
            return true;
        }

        private DBPropSet CommandPropertySets() {
            DBPropSet propSet = null;

            bool keyInfo = (0 != (CommandBehavior.KeyInfo & this.commandBehavior));

            // always set the CommandTimeout value?
            int count = (_executeQuery ? (keyInfo ? 4 : 2) : 1);

            if (0 < count) {
                propSet = new DBPropSet(1);

                tagDBPROP[] dbprops = new tagDBPROP[count];

                dbprops[0] = new tagDBPROP(ODB.DBPROP_COMMANDTIMEOUT, false, CommandTimeout);

                if (_executeQuery) {
                    // 'Microsoft.Jet.OLEDB.4.0' default is DBPROPVAL_AO_SEQUENTIAL
                    dbprops[1] = new tagDBPROP(ODB.DBPROP_ACCESSORDER, false, ODB.DBPROPVAL_AO_RANDOM); // MDAC 73030

                    if (keyInfo) {
                        // 'Unique Rows' property required for SQLOLEDB to retrieve things like 'BaseTableName'
                        dbprops[2] = new tagDBPROP(ODB.DBPROP_UNIQUEROWS, false, keyInfo);

                        // otherwise 'Microsoft.Jet.OLEDB.4.0' doesn't support IColumnsRowset
                        dbprops[3] = new tagDBPROP(ODB.DBPROP_IColumnsRowset, false, true);
                    }
                }
                propSet.SetPropertySet(0, OleDbPropertySetGuid.Rowset, dbprops);
            }
            return propSet;
        }

        internal Bindings TakeBindingOwnerShip() {
            Bindings bindings = _dbBindings;
            _dbBindings = null;
            return bindings;
        }

        private void ValidateConnection(string method) {
            if (null == _connection) {
                throw ADP.ConnectionRequired(method);
            }
            _connection.CheckStateOpen(method);

            // user attempting to execute the command while the first dataReader hasn't returned
            // use the connection reference collection to see if the dataReader referencing this
            // command has been garbage collected or not.
            if (_hasDataReader) {
                if (_connection.HasLiveReader(this)) {
                    throw ADP.OpenReaderExists();
                }
                _hasDataReader = false;
            }
        }

        private void ValidateConnectionAndTransaction(string method) {
            ValidateConnection(method);
            _transaction = _connection.ValidateTransaction(Transaction, method);
            this.canceling = false;
        }
    }
}