interbase.html

通用的数据库中间库

            versions are supported also.</P>
            <P>For more details see <A 
            href="../HowTo/connect.html">How To - Connecting to databases</A>, <A 
            href="../OnLineDoc/Connection_Usage.html">SAConnection object</A>, <A 
            href="../OnLineDoc/Connection_Connect.html">SAConnection::Connect</A>.</P>
            <P>&nbsp;</P>
            
            <H3><A 
            name="Transaction isolation levels">Transaction isolation 
            levels</A>  </H3>
            <P>SQL-92 defines four isolation levels, all of 
            which are supported by SQLAPI++:</P>
            <UL>
                <LI>Read uncommitted (the lowest level where 
                transactions are isolated just enough to ensure that physically 
                corrupt data is not read) 
                <LI>Read committed 
                <LI>Repeatable read 
                <LI>Serializable (the highest level, where 
                transactions are completely isolated from one another)</LI></UL>
            <P>SQLAPI++ maps different isolation levels on 
            <STRONG>InterBase</STRONG> server in the following way:</P>
            <P> <STRONG 
            >SA_ReadUncommitted</STRONG> = isc_tpb_read_committed,    
            isc_tpb_rec_version<BR><STRONG> SA_ReadCommitted</STRONG> = isc_tpb_read_committed,  
             isc_tpb_no_rec_version<BR><STRONG> SA_RepeatableRead</STRONG> =    
            isc_tpb_consistency<BR><STRONG> SA_Serializable</STRONG> =   
            isc_tpb_concurrency</P>
            <P>For more details see <A 
            href="../OnLineDoc/Connection_setIsolationLevel.html">SAConnection::setIsolationLevel</A>.</P>
            <P>&nbsp;</P>
            
            <H3><A 
            name="Working with Long or Lob(CLob, BLob) data">Working with Long or Lob(CLob, 
            BLob) data</A>    </H3>
            <P> 
            SQLAPI++ supports four types for working with 
            Long or Lob(CLob, BLob) data:</P>
            <P>
            <TABLE border=1 cellPadding=1 cellSpacing=1 style="WIDTH: 100%" 
            width=100%>
                
                <TR bgColor=navy>
                    <TD><FONT color=white 
                        style="BACKGROUND-COLOR: #000080">Name</FONT></TD>
                    <TD><FONT color=white 
                        style="BACKGROUND-COLOR: #000080">C 
                        enum constant</FONT></TD>
                </TR>
                <TR>
                    <TD>LongBinary</TD>
                    <TD>SA_dtLongBinary</TD>
                </TR>
                <TR>
                    <TD>LongChar</TD>
                    <TD>SA_dtLongChar</TD>
                </TR>
                <TR>
                    <TD>BLob (Binary Large object)</TD>
                    <TD>SA_dtBLob</TD>
                </TR>
                <TR>
                    <TD>CLob (Character Large object)</TD>
                    <TD>SA_dtCLob</TD>
                </TR></TABLE></P>
            <P>The table below shows how SQLAPI++ data 
            types correspond with servers original data types:</P>
            <P><EM>SA_dtLongBinary</EM> &lt;= &gt; BLOB,  subtype 0<BR><EM>SA_dtLongChar</EM> 
            &lt;= &gt; 
            BLOB,  subtype 1<BR 
            ><EM>SA_dtBLob</EM> = &gt; BLOB,  subtype 
            0<BR><EM>SA_dtCLob 
            </EM>=&gt; BLOB, subtype 
            1</EM></P>
            <P>
            For more details see <A href="../HowTo/blobs.html">How To - Working with Long or Lob(CLob, BLob) data</A></P>
            <P>&nbsp;</P>
            
            <H3><A 
            name="Returning output parameters">Returning output 
            parameters</A>  </H3>
            <p>If <STRONG>InterBase</STRONG>
            stored procedure returns only one row of 
            output parameters (the most common case), you can get output 
            parameters' values immediately after calling <A href="../OnLineDoc/Command_Execute.html" >SACommand::Execute</A>
            using 
            appropriate <A href="../OnLineDoc/Param.html" >SAParam</A> 
            objects.</p>
            <P>In <STRONG>InterBase</STRONG> 
              stored procedures can also 
            return several rows of output parameters. In this case you should perform 
            a select from a procedure to return them as result set.</P>
            <P>For more details see <A 
            href="../OnLineDoc/Command_Execute.html" >SACommand::Execute</A>, 
            <A href="../OnLineDoc/Param_Usage.html" >SAParam 
            object</A>, <A 
            href="../HowTo/return_param.html" >How To - Returning Output Parameters</A>.</P>
            <P>&nbsp;</P>
            
            <H3><A name="Cancelling queries">Cancelling 
            queries</A> </H3>
            <P><STRONG>InterBase</STRONG> does not support cancelling 
            queries.</P>
            <P>&nbsp;</P>
            
            <H3><A 
            name="Connection and command options">Connection and command 
            options</A>   </H3>
            <P>A server specific option can be related with a command or with a 
            connection. A connection related option must be specified in a&nbsp; 
            <A href="../OnLineDoc/Connection.html" >SAConnection</A>
            object. A command related option 
            may be specified in either <A href="../OnLineDoc/Connection.html" >SAConnection</A>
            object or <A href="../OnLineDoc/Command_Usage.html" >SACommand</A> 
            object. </P>
            <P>Specific options for <STRONG> InterBase</STRONG>:</P>
            <P>
            <TABLE border=1 cellPadding=5 width=100%>
                <TBODY>
                <TR bgColor=#000094>
                    <TD width=17%>
                        <P><STRONG><FONT color=white face="">Option name</FONT>&nbsp; 
                        </STRONG></P></TD>
                    <TD>
                        <P><STRONG><FONT color=white face=""> Description</FONT> 
                        </STRONG></P></TD></TR>
                <TR>
                    <TD>
                        <P align=center><STRONG><STRONG><STRONG>SQLDialect</STRONG></STRONG> 
                        </STRONG></P></TD>
                    <TD>
                        <P>Declares the SQL Dialect for 
                        database access.<BR><STRONG>Command 
                        related.</STRONG><BR>Valid values: 
                        see InterBase documentation.<BR>
                       
                                
                         Default value is &quot;3&quot;.</P></TD></TR>
                <TR>
                    <TD><STRONG><STRONG>
                        <P align=center><STRONG><STRONG>
                        <STRONG><STRONG>isc_dbp_lc_ctype</STRONG></STRONG></STRONG> 
                        </STRONG></P></STRONG> 
                        </STRONG></TD>
                    <TD>
                        <P>Specifies the character set to 
                        be utilized. For more information see InterBase 
                        documentation.<BR><STRONG>Connection related.</STRONG> Should be 
                        specified before actual connection is made.<BR 
                        >Valid values: String containing 
                        character set name, see InterBase documentation.<BR 
                        >   
                                
                        Default value: see InterBase documentation.</P></TD></TR>
                <TR>
                    <TD>
                        <P align=center><STRONG><STRONG>
                        <STRONG><STRONG>isc_dbp_sql_role_name</STRONG></STRONG></STRONG> 
                        </STRONG></P>
                    <TD>
                        <P>Declares role name that should 
                        used for connection. For more information see InterBase 
                        documentation.<BR><STRONG>Connection related.</STRONG> Should be 
                        specified before actual connection is made.<BR 
                        >Valid values: see InterBase 
                        documentation.<BR>   
                                
                        Default value: see InterBase documentation.</P>
                <TR>
                    <TD><STRONG><STRONG>
                        <P><STRONG>isc_dpb_num_buffers</STRONG></P></STRONG> 
                        </STRONG></TD>
                    <TD>
                        <P>Declares the number of database cache buffers to 
                        allocate for use with the database. For more information 
                        see InterBase documentation.<BR><STRONG>Connection related</STRONG>. Should be 
                        specified before actual connection is made.<BR 
                        >Valid values: 10-255, see InterBase 
                        documentation.<BR>Default value: 
                        75, see InterBase documentation.</P></TD></TR>
                <TR>
                    <TD><STRONG><STRONG>
                        <P align=center><STRONG>CommitRetaining</STRONG></P></STRONG> 
                        </STRONG></TD>
                    <TD>
                        <P>Determines which function (<EM 
                        >isc_commit_transaction()</EM> or <EM 
                        >isc_commit_retaining()</EM>) 
                        SQLAPI++ calls&nbsp; to commit transactions.<BR 
                        ><EM>isc_commit_transaction()</EM> writes transaction 
                        changes permanently to a database, closes the result set 
                        associated with the transaction, and frees system 
                        resources assigned to the transaction for other uses. 
                        Active result sets are not preserved.<BR><EM>isc_commit_retaining()</EM> 
                        writes all pending changes to the database, ends the 
                        current transaction without closing its record stream 
                        and cursors and without freeing its system resources, 
                        then starts a new transaction and assigns the existing 
                        record streams and system resources to the new 
                        transaction. Active result sets are preserved. <BR 
                        >For more information see InterBase 
                        documentation (<EM>isc_commit_retaining()</EM> and <EM>isc_commit_transaction()</EM> functions). <BR 
                        ><STRONG>Connection related.</STRONG> Should