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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<section id="db_res_t" xmlns:xi="http://www.w3.org/2001/XInclude">
<sectioninfo>
<revhistory>
<revision>
<revnumber>$Revision$</revnumber>
<date>$Date$</date>
</revision>
</revhistory>
</sectioninfo>
<title>Type <type>db_res_t</type></title>
<para>
This type represents a result returned by <function>db_query</function>
function (see below). The result can consist of zero or more rows (see
<type>db_row_t</type> description).
</para>
<note>
<para>
A variable of type <type>db_res_t</type> returned by
<function>db_query</function> function uses dynamically allocated
memory, don't forget to call <function>db_free_result</function> if
you don't need the variable anymore. You will encounter memory
leaks if you fail to do this !
</para>
</note>
<para>
In addition to zero or more rows, each <type>db_res_t</type> object
contains also an array of <type>db_key_t</type> objects. The objects
represent keys (names of columns).
</para>
<programlisting>
typedef struct db_res {
struct {
db_key_t* keys; /* Array of column names */
db_type_t* types; /* Array of column types */
int n; /* Number of columns */
} col;
struct db_row* rows; /* Array of rows */
int n; /* Number of rows */
} db_res_t;
</programlisting>
<itemizedlist>
<listitem>
<para>
<function>RES_NAMES(res)</function> Macro.
</para>
<para>
Use this macro if you want to obtain pointer to an array of
cell names.
</para>
<example>
<title>RES_NAMES Macro</title>
<programlisting>
...
db_key_t* column_names = ROW_NAMES(row);
...
</programlisting>
</example>
</listitem>
<listitem>
<para>
<function>RES_COL_N(res)</function> Macro.
</para>
<para>
Use this macro if you want to get the number of columns in the result.
</para>
<example>
<title>RES_COL_N Macro</title>
<programlisting>
<![CDATA[
...
int ncol = RES_COL_N(res);
for(i = 0; i < ncol; i++) {
/* do something with the column */
}
...
]]>
</programlisting>
</example>
</listitem>
<listitem>
<para>
<function>RES_ROWS(res)</function> Macro.
</para>
<para>
Use this macro if you need to obtain pointer to array of rows.
</para>
<example>
<title>RES_ROWS Macro</title>
<programlisting>
...
db_row_t* rows = RES_ROWS(res);
...
</programlisting>
</example>
</listitem>
<listitem>
<para>
<function>RES_ROW_N(res)</function> Macro.
</para>
<para>
Use this macro if you need to obtain the number of rows in the
result.
</para>
<example>
<title>RES_ROW_N Macro</title>
<programlisting>
...
int n = RES_ROW_N(res);
...
</programlisting>
</example>
</listitem>
</itemizedlist>
</section>
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