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<HTML
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>MySQL bindings</TITLE
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>GNADE User's Guide: GNADE, The GNat Ada Database Environment; Version 1.2.0; Document Revision $Revision: 1.26 $</TH
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><DIV
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><H1
><A
NAME="MYSQL"
>Chapter 18. MySQL bindings</A
></H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="mysql.html#AEN530"
>The MYSQL API</A
></DT
><DT
><A
HREF="x555.htm"
>Building programs with MySQL</A
></DT
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><P
>      The following example is stored under ./samples/mysql. It 
      requires the installed client libraries of the MySQL product.
   </P
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN530"
>The MYSQL API</A
></H1
><P
>      An instance of the MySQL.Object type represents the data base
      on application level. All operations on the data base are performed
      on this data type.
   </P
><P
>      Each issued query is identified by a query id which issued 
      to refer to the query. 
   </P
><P
>      Every program has to connect and authorize at the data base. This 
      is done by the Methods User, Password and Connect as shown in the 
      example below.
   </P
><P
>      The data base is selected by the primitive Select_DB.
      <DIV
CLASS="EXAMPLE"
><P
><B
>Example 18-1. MySQL native binding - Connecting to the database.</B
></P
><PRE
CLASS="PROGRAMLISTING"
>&#13;with GNU.DB.MySQL;           use GNU.DB.MySQL;
with GNU.DB;                 use GNU.DB ;


   dBase      : MySQL.Object;
   qId        : MySQL.Query_ID;

begin
   Initialize( dBase );

   User(     dBase, "gnade" );
   Password( dBase, "" );
   Connect(  dBase, "localhost" );

   Select_DB( dBase, "testdb" );
   
       </PRE
></DIV
>
   </P
><P
>      A query is send by the method Query to the data base. The 
      query string is a normal SQL query or DML command. The 
      result set of a query is described by a so called query identifier 
      with the type Query_ID. The result set is generated at the time 
      where the Query method is executed.
   </P
><P
>      <DIV
CLASS="EXAMPLE"
><P
><B
>Example 18-2. MySQL native binding - Executing a query</B
></P
><PRE
CLASS="PROGRAMLISTING"
>   .....
   qID := Query( dBase, "select * from Test where id='Otto'");
   Put_Line( "Nbr of Rows:" &#38; Integer'Image(Nbr_of_Rows(dBase, qID)) );
   ....
      </PRE
></DIV
>
   </P
><P
>      The result set may be reed out by means of the Next method as 
      it is shown below.
   </P
><P
>      <DIV
CLASS="EXAMPLE"
><P
><B
>Example 18-3. MySQL native binding - Accessing the result set</B
></P
><PRE
CLASS="PROGRAMLISTING"
>      ........
      while true loop
         declare
            Insert_Time : Time;
         begin
            Nbr_Tuples := Nbr_Tuples + 1;
            Put_Line( "'" &#38; To_String( String_Field( dBase, qId, "id" ) ) &#38; "'" );
            Insert_Time := Date_Field( dBase, qID, 2);
            Next( dBase, qID );
         exception
            when Field_Parse_Error =&#62;
               Put_Line("Field parse error");
               Next( dBase, qID );
            when Others =&#62;
               raise;
         end;
      end loop;
      .........
      </PRE
></DIV
>
   </P
><P
>      After the result set has been processed the query context has to be 
      returned to MySQL via the Drop_Query method.
   </P
><P
>      If the application intends to disconnect completely, the data base 
      instance should be Finalized as shown below.
   </P
><P
>      <DIV
CLASS="EXAMPLE"
><P
><B
>Example 18-4. MySQL native binding - Dropping the query </B
></P
><PRE
CLASS="PROGRAMLISTING"
>   .....
   Drop_Query( dBase, qID );

   Finalize( dBase );
   .....
      </PRE
></DIV
>
   </P
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