PDOStatement::columnCount

说明

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