(PHP 5 >= 5.1.0, PECL pdo >= 0.1.0)
PDO::exec — Execute an SQL statement and return the number of affected rows
PDO::exec() executes an SQL statement in a single function call, returning the number of rows affected by the statement.
PDO::exec() does not return results from a SELECT statement. For a SELECT statement that you only need to issue once during your program, consider issuing PDO::query(). For a statement that you need to issue multiple times, prepare a PDOStatement object with PDO::prepare() and issue the statement with PDOStatement::execute().
The SQL statement to prepare and execute.
Data inside the query should be properly escaped.
PDO::exec() returns the number of rows that were modified or deleted by the SQL statement you issued. If no rows were affected, PDO::exec() returns 0.
此函数可能返回布尔值 FALSE，但也可能返回等同于 FALSE 的非布尔值，例如 0 或 ""(空串)。请阅读 布尔类型章节以获取更多信息。应使用 === 运算符 来测试此函数的返回值。
The following example incorrectly relies on the return value of PDO::exec(), wherein a statement that affected 0 rows results in a call to die():
<?php
$db->exec() or die(print_r($db->errorInfo(), true));
?>
Example #1 Issuing a DELETE statement
Count the number of rows deleted by a DELETE statement with no WHERE clause.
<?php
$dbh = new PDO('odbc:sample', 'db2inst1', 'ibmdb2');
/* Delete all rows from the FRUIT table */
$count = $dbh->exec("DELETE FROM fruit WHERE colour = 'red'");
/* Return number of rows that were deleted */
print("Deleted $count rows.\n");
?>
以上例程会输出：
Deleted 1 rows.