PDO->errorInfo()
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.
PDO->exec()
(PHP 5 >= 5.1.0, PECL pdo:0.1-1.0.3)
PDO->exec() — Execute an SQL statement and return the number of affected rows
Description
PDO
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().
Parameters
- statement
-
The SQL statement to prepare and execute.
Return Values
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.
Warning
This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE, such as 0 or "". Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.
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
$db->exec() or die($db->errorInfo());
?>
Examples
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");
?>
The above example will output:
Deleted 1 rows.
add a note
User Contributed NotesPDO->exec()
blah at whatevr dot com
05-Sep-2007 11:07
05-Sep-2007 11:07
jon at chem dot umass dot edu
10-May-2007 05:12
10-May-2007 05:12
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.