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<H1>odbc</H1>
</CENTER>

<H3>MODULE</H3>
<DIV CLASS=REFBODY>
odbc
</DIV>

<H3>MODULE SUMMARY</H3>
<DIV CLASS=REFBODY>
Erlang ODBC application
</DIV>

<H3>DESCRIPTION</H3>
<DIV CLASS=REFBODY>

<P> This application provides an Erlang interface to communicate
with relational SQL-databases. It is built on top of Microsofts
ODBC interface and therefore requires that you have an ODBC driver
to the database that you want to connect to.
<P>
<TABLE CELLPADDING=4>
  <TR>
    <TD VALIGN=TOP><IMG ALT="Note!" SRC="note.gif"></TD>
    <TD>

<P> The functions <CODE>first/[1,2]</CODE>, <CODE>last/[1,2]</CODE>,
<CODE>next/[1,2]</CODE>, <CODE>prev[1,2]</CODE> and <CODE>select/[3,4]</CODE>
assumes there is a result set associated with the connection to
work on. Calling the function <CODE>select_count/[2,3]</CODE>
associates such a result set with the connection. Calling
select_count again will remove the current result set
association and create a new one. Calling a function which dose
not operate on an associated result sets, such as
<CODE>sql_query/[2,3]</CODE>, will remove the current result set
association.
<P>Alas some drivers only support sequential traversal of the
result set, e.i. they do not support what in the ODBC world is
known as scrollable cursors. This will have the effect that
functions such as <CODE>first/[1,2]</CODE>, <CODE>last/[1,2]</CODE>,
<CODE>prev[1,2]</CODE>, etc will return <CODE>{error,
driver_does_not_support_function}</CODE>
    </TD>
  </TR>
</TABLE>

</DIV>

<H3> COMMON DATA TYPES </H3>
<DIV CLASS=REFBODY>

<P> Here follows type definitions that are used by more than one
function in the ODBC API. 
<P>
<TABLE CELLPADDING=4>
  <TR>
    <TD VALIGN=TOP><IMG ALT="Note!" SRC="note.gif"></TD>
    <TD>

<P>The type <CODE>TimeOut</CODE> has the default value
        <CODE>infinity</CODE>, so for instance:<BR>

        commit(Ref, CommitMode) is the same as
        commit(Ref, CommitMode, infinity). If the
        timeout expires the client will exit with the reason
        timeout.     </TD>
  </TR>
</TABLE>

<PRE>
 connection_reference() - as returned by connect/2
</PRE>

<PRE>
 time_out() = milliseconds() | infinity
</PRE>

<PRE>
 milliseconds() = integer() &#62;= 0 
</PRE>

<PRE>
 common_reason() = connection_closed | term() - some kind of
                 explanation of what went wrong
</PRE>

<PRE>
 string() = list of ASCII characters
</PRE>

<PRE>
 col_name() = string() - Name of column in the result set
</PRE>

<PRE>
 col_names() - [col_name()] - e.g. a list of the names of the
           selected columns in the result set. 
</PRE>

<PRE>
 row() = {value()} - Tuple of column values e.g. one row of the
           result set. 
</PRE>

<PRE>
 value() = null | term() - A column value. 
</PRE>

<PRE>
 rows() = [row()] - A list of rows from the result set.
</PRE>

<PRE>
 result_tuple() =
      {updated, n_rows()} | {selected, col_names(), rows()}
</PRE>

<PRE>
 n_rows() = integer() - The number of affected rows for UPDATE,
           INSERT, or DELETE queries. For other query types the value
           is driver defined, and hence should be ignored.
</PRE>

<PRE>
 odbc_data_type() = sql_integer | sql_smallint | sql_tinyint |
      {sql_decimal, precison(), scale()} |
      {sql_numeric, precison(), scale()} |
      {sql_char, size()} | {sql_varchar, size()} | {sql_float, precision()} |
      {sql_float, precision()} | sql_real | sql_double | sql_bit | atom()
    
</PRE>

<PRE>
 precision() = integer()
</PRE>

<PRE>
 scale() = integer()
</PRE>

<PRE>
 size() = integer()
</PRE>

</DIV>

<H3> ERROR HANDLING </H3>
<DIV CLASS=REFBODY>

<P>The error handling strategy and possible errors sources are
described in the Erlang ODBC <A HREF="error_handling.html">User's
Guide.</A> 
</DIV>

<H3>EXPORTS</H3>

<P><A NAME="commit/2"><STRONG><CODE> commit(Ref, CommitMode) -&#62;</CODE></STRONG></A><BR>
<A NAME="commit/3"><STRONG><CODE> commit(Ref, CommitMode, TimeOut) -&#62;
        ok | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference() </CODE></STRONG><BR>
<STRONG><CODE> CommitMode = commit | rollback</CODE></STRONG><BR>
<STRONG><CODE> TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> Reason = not_an_explicit_commit_connection |
         process_not_owner_of_odbc_connection | common_reason()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Commits or rollbacks a transaction. Needed on connections
        where automatic commit is turned off.
</DIV>

<P><A NAME="connect/2"><STRONG><CODE> connect(ConnectStr, Options) -&#62;
        {ok, Ref} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> ConnectStr = string()</CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 An example of a connection string:
         <CODE>&#34;DSN=sql-server;UID=alladin;PWD=sesame&#34;</CODE> where DSN is
         your ODBC Data Source Name, UID is a database user id and
         PWD is the password for that user. These are usually the
         attributes required in the connection string, but some
         drivers have other driver specific attributes, for example
         <CODE>&#34;DSN=Oracle8;DBQ=gandalf;UID=alladin;PWD=sesame&#34;</CODE>
         where DBQ is your TNSNAMES.ORA entry name e.g. some Oracle
         specific configuration attribute.
</DIV>
<STRONG><CODE> Options = [] | [option()]</CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 All options has default values. 
</DIV>
<STRONG><CODE> option() = {auto_commit, auto_commit_mode()} | {timeout,
         milliseconds()} | {tuple_row, tuple_mode()} |
         {scrollable_cursors, use_srollable_cursors()} |
         {trace_driver, trace_mode()} </CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 The default timeout is infinity 
</DIV>
<STRONG><CODE> auto_commit_mode() = on | off </CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 Default is on.
</DIV>
<STRONG><CODE> tuple_mode() = on | off </CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 Default is on. The option is deprecated and should not be used
        in new code.
</DIV>
<STRONG><CODE> use_srollable_cursors() = on | off </CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 Default is on.
</DIV>
<STRONG><CODE> trace_mode() = on | off </CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 Default is off.
</DIV>
<STRONG><CODE> Ref = connection_reference() - should be used to acess the
         connection. </CODE></STRONG><BR>
<STRONG><CODE> Reason = port_program_executable_not_found | common_reason()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Opens a connection to the database. The connection is
         associated with the process that created it and can only be
         accessed through it. This funtion may spawn new processes
         to handle the connection. These processes will terminate if
         the process that created the connection dies or if you call
         disconnect/1.
        
<P> If automatic commit mode is turned on, each query will be
        considered as an individual transaction and will be
        automaticly commited after it has been executed. If you want
        more than one query to be part of the same transaction the automatic
        commit mode should be turned off. Then you will have to call
        commit/3 explicitly to end a transaction. 
<P> As default result sets are returned as a lists of
         tuples. The <CODE>TupleMode</CODE> option still exists to keep some
         degree of backwards compatiblity. If the option is set to
         off, result sets will be returned as a lists of lists
         instead of a lists of tuples.
        
<P>Scrollable cursors are nice but causes some overhead. For
        some connections speed might be more important than flexible
        data access and then you can disable scrollable cursor for a
        connection, limiting the API but gaining speed
        
<P> If trace mode is turned on this tells the ODBC driver to
         write a trace log to the file SQL.LOG that is placed in the
         current directory of the erlang emulator. This information
         may be useful if you suspect there might be a bug in the
         erlang ODBC application, and it might be relevant for you to
         send this file to our support. Otherwise you will probably
         not have much use of this.
<P>
<TABLE CELLPADDING=4>
  <TR>
    <TD VALIGN=TOP><IMG ALT="Note!" SRC="note.gif"></TD>
    <TD>

<P>For more information about the <CODE>ConnectStr</CODE> see
         description of the function SQLDriverConnect in [1].    </TD>
  </TR>
</TABLE>

</DIV>

<P><A NAME="disconnect/1"><STRONG><CODE> disconnect(Ref) -&#62; ok | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE> Reason = process_not_owner_of_odbc_connection</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Closes a connection to a database. This will also
         terminate all processes that may have been spawned 
         when the connection was opened. This call will always succeed.
         If the connection can not be disconnected gracefully it will
         be brutally killed. However you may receive an error message
         as result if you try to disconnect a connection started by another
         process.
         <A NAME="describe_table"><!-- Empty --></A>
</DIV>

<P><A NAME="describe_table/2"><STRONG><CODE> describe_table(Ref, Table) -&#62; </CODE></STRONG></A><BR>
<A NAME="describe_table/3"><STRONG><CODE> describe_table(Ref, Table, Timeout) -&#62;
        {ok, Description} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE>Table = string() - Name of databas table.</CODE></STRONG><BR>
<STRONG><CODE> TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE>Description = [{col_name(), odbc_data_type()}]</CODE></STRONG><BR>
<STRONG><CODE> Reason = common_reason()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Queries the database to find out the ODBC data types of the
         columns of the table <CODE>Table</CODE>. 
</DIV>

<P><A NAME="first/1"><STRONG><CODE> first(Ref) -&#62;</CODE></STRONG></A><BR>
<A NAME="first/2"><STRONG><CODE> first(Ref, Timeout) -&#62;
        {selected, ColNames, Rows} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE> TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> ColNames = col_names() </CODE></STRONG><BR>
<STRONG><CODE> Rows = rows()</CODE></STRONG><BR>
<STRONG><CODE> Reason = result_set_does_not_exist | driver_does_not_support_function |
         scrollable_cursors_disabled | process_not_owner_of_odbc_connection | common_reason() </CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Returns the first row of the result set and positions a
         cursor at this row.
</DIV>

<P><A NAME="last/1"><STRONG><CODE>last(Ref) -&#62;</CODE></STRONG></A><BR>
<A NAME="last/2"><STRONG><CODE>last(Ref, TimeOut) -&#62;
        {selected, ColNames, Rows} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE> TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> ColNames = col_names() </CODE></STRONG><BR>
<STRONG><CODE> Rows = rows()</CODE></STRONG><BR>
<STRONG><CODE> Reason = result_set_does_not_exist | driver_does_not_support_function |
         scrollable_cursors_disabled | process_not_owner_of_odbc_connection | common_reason() </CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Returns the last row of the result set and positions a
        cursor at this row.
</DIV>

<P><A NAME="next/1"><STRONG><CODE> next(Ref) -&#62; </CODE></STRONG></A><BR>
<A NAME="next/2"><STRONG><CODE> next(Ref, TimeOut) -&#62;
        {selected, ColNames, Rows} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE> TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> ColNames = col_names() </CODE></STRONG><BR>
<STRONG><CODE> Rows = rows()</CODE></STRONG><BR>
<STRONG><CODE> Reason = result_set_does_not_exist | process_not_owner_of_odbc_connection | common_reason() </CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Returns the next row of the result set relative the
         current cursor position and positions the cursor at this
         row. If the cursor is positioned at the last row of the
         result set when this function is called the returned value
         will be <CODE>{selected, ColNames,[]}</CODE> e.i. the list of row
         values is empty indicating that there is no more data to fetch.
         <A NAME="param_query"><!-- Empty --></A>
</DIV>

<P><A NAME="param_query/3"><STRONG><CODE> param_query(Ref, SQLQuery, Params) -&#62; </CODE></STRONG></A><BR>
<A NAME="param_query/4"><STRONG><CODE> param_query(Ref, SQLQuery, Params, TimeOut) -&#62;
        ResultTuple | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE>SQLQuery = string() - a SQL query with parameter
         markers/place holders in form of question marks.</CODE></STRONG><BR>
<STRONG><CODE>Params = [{odbc_data_type(), [value()]}]</CODE></STRONG><BR>
<STRONG><CODE>TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE>Values = term() - Must be consistent with the Erlang data type
         that corresponds to the ODBC data type ODBCDataType</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Executes a parameterized SQL query. For an
         example see the <A HREF="getting_started.html#param_query">     &#34;Using the Erlang API&#34;</A> in the Erlang ODBC 
         User's Guide.
        
<P>
<TABLE CELLPADDING=4>
  <TR>
    <TD VALIGN=TOP><IMG ALT="Note!" SRC="note.gif"></TD>
    <TD>

<P>Use the function describe_table/[2,3] to find out which
         ODBC data type that is expected for each column of that
         table. If a column has a data type that is described with
         capital letters, alas it is not currently supported by the
         param_query function. Too know which Erlang data type
         corresponds to an ODBC data type see the Erlang to ODBC
         data type<A HREF="databases.html#type"> mapping
         </A> in the User's Guide.
             </TD>
  </TR>
</TABLE>

</DIV>

<P><A NAME="prev/1"><STRONG><CODE> prev(Ref) -&#62; </CODE></STRONG></A><BR>
<A NAME="prev/2"><STRONG><CODE>prev(ConnectionReference, TimeOut) -&#62;
        {selected, ColNames, Rows} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE>TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> ColNames = col_names() </CODE></STRONG><BR>
<STRONG><CODE> Rows = rows()</CODE></STRONG><BR>
<STRONG><CODE> Reason = result_set_does_not_exist | driver_does_not_support_function |
         scrollable_cursors_disabled | process_not_owner_of_odbc_connection | common_reason() </CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Returns the previous row of the result set relative the
         current cursor position and positions the
         cursor at this row.
</DIV>

<P><A NAME="sql_query/2"><STRONG><CODE>sql_query(Ref, SQLQuery) -&#62; </CODE></STRONG></A><BR>
<A NAME="sql_query/3"><STRONG><CODE>sql_query(Ref, SQLQuery, TimeOut) -&#62;
        ResultTuple | [ResultTuple] |{error, Reason}
</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE> SQLQuery = string() - The string may be composed by several
        SQL-queries separated by a &#34;;&#34;, this is called a
        batch. </CODE></STRONG><BR>
<STRONG><CODE>TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> ResultTuple = result_tuple() </CODE></STRONG><BR>
<STRONG><CODE> Reason = process_not_owner_of_odbc_connection | common_reason() </CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Executes a SQL query or a batch of SQL queries. If it
        is a SELECT query the result set is returned, on the format
        <CODE>{selected, ColNames, Rows}</CODE>. For other query types the
        tuple <CODE>{updated, NRows}</CODE> is returned, and for batched
        queries, if the driver supports them, this function can also
        return a list of result tuples.
<P>
<TABLE CELLPADDING=4>
  <TR>
    <TD VALIGN=TOP><IMG ALT="Note!" SRC="note.gif"></TD>
    <TD>

<P>Some drivers may not have the information of the number
         of affected rows available and then the return value may
         be <CODE>{updated, undefined} </CODE>. 
<P>The list of column names is ordered in the same way as the
         list of values of a row, e.g. the first <CODE>ColName</CODE> is
         associated with the first <CODE>Value</CODE> in a <CODE>Row</CODE>.
             </TD>
  </TR>
</TABLE>
<BR>

</DIV>

<P><A NAME="select_count/2"><STRONG><CODE> select_count(Ref, SelectQuery) -&#62; </CODE></STRONG></A><BR>
<A NAME="select_count/3"><STRONG><CODE> select_count(Ref, SelectQuery, TimeOut) -&#62;
        {ok, NrRows} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE> SelectQuery = string()</CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 SQL SELECT query.
</DIV>
<STRONG><CODE>TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> NrRows = n_rows()</CODE></STRONG><BR>
<STRONG><CODE> Reason = process_not_owner_of_odbc_connection |
         common_reason() </CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P> Executes a SQL SELECT query and associates the result set
         with the connection. A cursor is positioned before the first
         row in the result set and the tuple <CODE>{ok, NrRows}</CODE> is
         returned. 
<P>
<TABLE CELLPADDING=4>
  <TR>
    <TD VALIGN=TOP><IMG ALT="Note!" SRC="note.gif"></TD>
    <TD>

<P>Some drivers may not have the information of the number of
         rows in the result set, then <CODE>NrRows</CODE> will have the value
         <CODE>undefined</CODE>.     </TD>
  </TR>
</TABLE>

</DIV>

<P><A NAME="select/3"><STRONG><CODE> select(Ref, Position, N) -&#62;
</CODE></STRONG></A><BR>
<A NAME="select/4"><STRONG><CODE> select(Ref, Position, N, TimeOut) -&#62;
        {selected, ColNames, Rows} | {error, Reason} </CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE> Ref = connection_reference()</CODE></STRONG><BR>
<STRONG><CODE> Position = next | {relative, Pos} | {absolute, Pos} </CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 Selection strategy, determines at which row in the
        result set to start the selection.
</DIV>
<STRONG><CODE> Pos = integer() </CODE></STRONG><BR>

<DIV CLASS=REFBODY>
 Should indicate a row number in the result set.
        When used together with the option <CODE>relative</CODE> it
        will be used as an offset from the current cursor position,
        when used together with the option <CODE>absolute</CODE> it will
        be interpreted as a row number.
</DIV>
<STRONG><CODE> N = integer() </CODE></STRONG><BR>
<STRONG><CODE>TimeOut = time_out()</CODE></STRONG><BR>
<STRONG><CODE> Reason = result_set_does_not_exist | driver_does_not_support_function |
         scrollable_cursors_disabled | process_not_owner_of_odbc_connection | common_reason() </CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Selects <CODE>N</CODE> consecutive rows of the result set. If
         <CODE>Position</CODE> is <CODE>next</CODE> it is semanticly equivalent
         of calling <CODE>next/[1,2]</CODE> <CODE>N</CODE> times. If
         <CODE>Position</CODE> is <CODE>{relative, Pos}</CODE>, <CODE>Pos</CODE> will be
         used as an offset from the current cursor position to
         determine the first selected row. If <CODE>Position</CODE> is
         <CODE>{absolute, Pos}</CODE>, <CODE>Pos</CODE> will be the number of the
         first row selected. After this function has returned the
         cursor is positioned at the last selected row. If there is
         less then <CODE>N</CODE> rows left of the result set the length of
         <CODE>Rows</CODE> will be less than <CODE>N</CODE>. If the first row to
         select happens to be beyond the last row of the result set,
         the returned value will be <CODE>{selected, ColNames,[]}</CODE>
         e.i. the list of row values is empty indicating that there
         is no more data to fetch.

</DIV>

<H3>REFERENCES</H3>
<DIV CLASS=REFBODY>

<P>[1]: Microsoft ODBC 3.0, Programmer's Reference and SDK Guide<BR>

See also http://msdn.microsoft.com/

</DIV>

<H3>AUTHORS</H3>
<DIV CLASS=REFBODY>
Ingela Anderton Andin - support@erlang.ericsson.se<BR>

</DIV>
<CENTER>
<HR>
<SMALL>odbc 2.0.6<BR>
Copyright &copy; 1991-2006
<A HREF="http://www.erlang.se">Ericsson AB</A><BR>
</SMALL>
</CENTER>
</BODY>
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