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<h1>Fetching result set</h1>
</center>
<p>To execute a command and process a result set you should do the following:</p>
<OL>
<LI>Create a command object and set a
command text.
<LI>Bind input parameters (if needed).
<LI>Execute the command.
<LI>Process the result set.</LI></OL>
<p>For example, let's fetch rows from the table
<EM>EMPLOYEES ( NAME CHAR(25), AGE
INTEGER)</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,
"select name, age from employees where
age>:1");</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. This command will select all
rows from the table <EM>EMPLOYEES</EM> where the value of field
<EM>AGE</EM> more than some input value.</p>
<H4>Step 2. Binding input parameters.</H4>
<p>To associate a value with input variable use
<A
href="../OnLineDoc/Command_operator_bind.html">SACommand::operator<<</A>:</p>
<p><FONT face=System>cmd <<
25;</FONT></p>
<p>This line sets the input parameter marked by
<EM>:1</EM> to value <EM>25</EM>.</p>
<p>The Library provides several ways for
binding input variables. To get more details see <A
href="bind.html">Binding input parameters</A>.</p>
<H4>Step 3. Execute the command.</H4>
<P>To execute a command use <A
href="../OnLineDoc/Command_Execute.html">SACommand::Execute</A>
method:</P>
<P><FONT face=System>cmd.Execute();</FONT></P>
<P>This command selects all rows from the table
where field <EM>AGE</EM> value more than <EM>25</EM>. The result of
command execution is the <EM>result set</EM> - a set of rows
corresponding with the request. </P>
<P>To check whether a result set exists after
the command execution use <A
href="../OnLineDoc/Command_isResultSet.html">SACommand::isResultSet</A>
method:</P>
<P><FONT face=System>bool is_result =
cmd.isResultSet(); <BR></FONT></P>
<H4>Step 4. Processing the result set.</H4>
<P>After the command execution a set of <A
href="../OnLineDoc/Field.html">SAField</A>objects is created
implicitly. Each <A href="../OnLineDoc/Field.html">SAField</A>
object represents a column in the result set. To get the number of
columns in the result set call <A
href="../OnLineDoc/Command_FieldCount.html">SACommand::FieldCount</A>
method:</P>
<P><FONT face=System>long col_count =
cmd.FieldCount();</FONT></P>
<P>Each field can be reached by its name or
position. To get a field information (name, type, size, etc)
directly after the command execution you can call <A
href="../OnLineDoc/Command_Field.html">SACommand::Field</A>
method:</P>
<P><FONT face=System>SAField& Field =
cmd.Field("age");</FONT></P>
<P>The line above associates the column
<EM>AGE</EM> in the result set with <EM>Field</EM> variable. We can
do the same getting column <EM>AGE</EM> by its position in the
result set:</P>
<P><FONT face=System>SAField& Field =
cmd.Field(2);</FONT></P>
<P>A field value is updated only after row
fetching. To fetch row by row from the result set use <A
href="../OnLineDoc/Command_FetchNext.html">SACommand::FetchNext</A>
method:</P>
<P><FONT
face=System>while(cmd.FetchNext())<BR>
printf("Name: %s, age: %d \n",
<BR>
cmd.Field("name").asString(),
<BR>
cmd.Field("age").asLong()); </FONT></P>
<P>In example above we reached a field value
accessing appropriated <A href="../OnLineDoc/Field.html">SAField</A>
object. Another way to get a field value is to use <A
href="../OnLineDoc/Command_operator_get.html">SACommand::operator[]</A>:</P>
<P><FONT
face=System>while(cmd.FetchNext())<BR>
printf("Name: %s, age: %d \n",
<BR>
cmd[1].asString(),
<BR>
cmd[2].asLong()); </FONT></P>
<P><BR>
<P>You can use <A
href="../OnLineDoc/Field.html"><STRONG>SAField</A>
operators</STRONG> for quick accessing values. In this case you can
organize a fetching process as shown below:</P>
<P><FONT
face=System>while(cmd.FetchNext())<BR>{<BR> SAString sName =
cmd.Field("name");<BR> long nAge =
cmd.Field("age");<BR> printf("Name:
%s, age: %d \n", sName, nAge);<BR>
}
<BR>
</FONT><BR>or another variant:</P>
<P><FONT
face=System>while(cmd.FetchNext())<BR>{<BR> SAString sName =
cmd[1];<BR> long nAge =
cmd[2];<BR> printf("Name: %s, age: %d
\n", sName, nAge);<BR>
}
<BR>
</FONT></P>
<P>Processing Long, BLob and CLob data can
have some differences from processing other data types. <FONT
color=black face="">See <A href="blobs.html" >Working with Long or
Lob(CLob, BLob) Data</A> to get more information.</FONT></P>
<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>
<p> </p>
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