PHP : Function Reference : PDO Functions : PDO->exec() PHP Examples Tutorials References

Example 1760. 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");
?>

The above example will output:

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Deleted 1 rows.

Code Examples / Notes » pdo_exec

You can't use it not only with SELECT statement, but any statement that might return rows. "OPTIMIZE table" is such example (returns some rows with optimization status). If you do, PDO will lock-up with the "Cannot execute queries while other unbuffered queries are active." nonsense.

If you do this: $res = $dbh->query("SELECT * FROM sessions WHERE session_id = '$p_sessID'"); $l_records = $res->fetch(PDO::FETCH_ASSOC); if( $l_records ) { // ...update session-data $l_theQuery = "UPDATE sessions SET session_expires='$newExp', session_data='$p_sessData' WHERE session_id='$p_sessID'"; echo $l_theQuery; $l_stmt = $this->db->prepare($l_theQuery); if ( $l_stmt ) { $l_rows = $l_stmt->execute(); } } You will get nothing. But do this: $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING); Prior to the code above, you will get this: "PDO::prepare(): SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute." So, instead of fetch(), use fetchAll(), it will make you less insane. Incidentally, the INSERT statement that I was issuing, if the record that I needed to update didn't yet exist, after the initial fetch() command worked perfectly. Changing to fetchAll() fixed it.

PDO->exec()

Execute an SQL statement and return the number of affected rows ()

Example 1760. Issuing a DELETE statement

Code Examples / Notes » pdo_exec

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