PDOStatement::columnCount

(no version information, might be only in CVS)

PDOStatement::columnCount --  Returns the number of columns in the result set

说明

int PDOStatement::columnCount ( void )

Use PDOStatement::columnCount() to return the number of columns in the result set represented by the PDOStatement object.

If the PDOStatement object was returned from PDO::query(), the column count is immediately available.

If the PDOStatement object was returned from PDO::prepare(), an accurate column count will not be available until you invoke PDOStatement::execute().

返回值

Returns the number of columns in the result set represented by the PDOStatement object. If there is no result set, PDOStatement::columnCount() returns 0.

范例

例子 1. Counting columns

This example demonstrates how PDOStatement::columnCount() operates with and without a result set.

<?php
$dbh
= new PDO('odbc:sample', 'db2inst1', 'ibmdb2');

$sth = $dbh->prepare("SELECT name, colour FROM fruit");

/* Count the number of columns in the (non-existent) result set */
$colcount = $sth->columnCount();
print(
"Before execute(), result set has $colcount columns (should be 0)\n");

$sth->execute();

/* Count the number of columns in the result set */
$colcount = $sth->columnCount();
print(
"After execute(), result set has $colcount columns (should be 2)\n");

?>

上例将输出:

Before execute(), result set has 0 columns (should be 0)
After execute(), result set has 2 columns (should be 2)

参见

PDO::prepare()
PDOStatement::execute()
PDOStatement::rowCount()