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<A href="commands.html" style ="TEXT-DECORATION: none" >
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Executing an SQL command</A> </FONT> </td>
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<h1>Executing an SQL command</h1>
</center>
<p> To execute an SQL command you should do the following:</p>
<OL>
<LI>Create a command object and set a
command text.
<LI>Bind input parameters.
<LI>Execute the command.
<LI>Processing output parameters and result set.</LI></OL>
<P> In this section we'll consider a commands like INSERT, SELECT
and UPDATE that do not involve fetching data. To execute SELECT
command or a stored procedures see <A href="fetch.html">Fetching
result set</A>
and <A href="procedures.html">Executing stored
procedures</A>
sections.</P>
<P>In the following example we assume that the table <EM>EMPLOYEES (
NAME CHAR(25), AGE INTEGER)</EM> exists on the database
<EM>Demo</EM>. </P>
<H4>Step 1. Creating a command object and setting a command
text.</H4>
<P>To execute a command we need two objects: <A href="../OnLineDoc/Connection.html" >SAConnection</A>
(connection object) and <A href="../OnLineDoc/Command.html" >SACommand</A>
(command object).</P>
<p><STRONG><FONT face=""
size=2><FONT face=System><FONT>SACommand cmd(&Connection,
"insert into employees (name, age) values (:1,
:2)");</FONT></FONT></FONT></STRONG><FONT
><FONT face=System></FONT></FONT> </p>
<p>The line above creates a command object <EM
>cmd</EM> based on previously created and
connected connection object <EM>Connection</EM>
(for creating and connection <EM>Connection</EM>
object see <A href="connect.html" >Connecting to
databases</A> ). Second parameter is the command text.
The command text can also be provided using <A href="../OnLineDoc/Command_setCommandText.html" >SACommand::setCommandText</A>
method.</p>
<p><FONT face=System size=2><STRONG>SACommand cmd(&Connection);<BR
>cmd.setCommandText("insert into employees (name, age)
values (:1, :2)");</STRONG></FONT> </p>
<p><FONT face=System size=2><STRONG></STRONG></FONT> </p>
<H4>Step 2. Bind input parameters.</H4>
<P>Binding some values to the command is like a filling in the gaps
in the SQL command statement (marked by <EM>:1, :2, :3, ...,
:n</EM>) with actual data values. The data values can be constants
or program variables of appropriate types. To associate a command
object with these bind variables you can use the <A
href="../OnLineDoc/Command_operator_bind.html">SACommand::operator<<</A>
as shown below:</P>
<P><FONT face=System>cmd << "Tom Patt" <<
30;</FONT></P>
<P>The order that you associate the values is important (i.e. the
first '<<' associates a bind with <EM>:1</EM>, the second
'<<' with <EM>:2</EM> ). </P>
<P>The another way to bind input variables is directly assigning a
value with <A href="../OnLineDoc/Param.html">SAParam</A>
object which represents a command parameter. To get appropriated
parameter object by its position in SQL statement use <A
href="../OnLineDoc/Command_Param.html">SACommand::Param</A>
method:</P>
<P><FONT face=System>cmd.Param(1).setAsString() = "Tom
Patt";<BR>cmd.Param(2).setAsLong() = 30;</FONT></P>
<P>More details about binding input variables see in <A
href="bind.html">Binding input parameters</A> section.</P>
<P> </P>
<H4>Step 3. Executing the command.</H4>
<P>Finally we execute the command, which results in the string being
inserted into column <EM>NAME</EM>, and the number being inserted
into column <EM>AGE</EM>.</P>
<P><FONT face=System>cmd.Execute();</FONT></P>
<P>If you want to see the number of rows affected by the command
execution use <A
href="../OnLineDoc/Command_RowsAffected.html">SACommand::RowsAffected</A>
method:</P>
<P><FONT face=System>int nRows = cmd.RowsAffected();</FONT></P>
<P>If you want to insert another row of new data, you just have to
associate the new bind values with the object and repeat the
bind/execute part again: </P>
<P><FONT face=System>cmd << "Nick Barry" <<
37;<BR>cmd.Execute();</FONT></P>
<P> </P>
<H4>Step 4. Processing output parameters and result set.</H4>
<P>Processing output parameters and result set
is not actual for INSERT, UPDATE and DELETE commands, that's why we
discuss this questions in other sections.</P>
<P>For processing result set (if any) see <A href="fetch.html" >Fetching result set</A>.</P>
<P>For processing output parameters (if any)
see <A href="return_param.html">Returning output
parameters</A>. </P>
<p>
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<h3>Problems and Questions</h3>
<p>If you don't find the answer to
you questions or have some problems on using the
Library, please, send e-mail to <A href="mailto:howto@sqlapi.com" >howto@sqlapi.com</A>. </p>
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