Using MySQL stored procedures with PHP mysqli

A couple of weeks ago a friend of mine asked me how to use MySQL stored procedures with PHP's mysqli API. Out of curiosity I asked another friend, a team lead, how things where going with their PHP MySQL project, for which they had planned to have most of their business logic in stored procedures. I got an email in reply stating something along the lines: "Our developers found that mysqli does not support stored procedures correctly. We use PDO.". Well, the existing documentation from PHP 5.0 times is not stellar, I confess. But still, that's a bit too mucha€¦ it ain't that difficult. And, it works.

Using stored procedures with mysqli

The MySQL database supports stored procedures. A stored procedure is a subroutine stored in the database catalog. Applications can call and execute the stored procedure. The CALL SQL statement is used to execute a stored procedure.

Parameter

Stored procedures can have IN, INOUT and OUT parameters. The mysqli interface has no special notion for the different kinds of parameters.

IN parameter

Input parameters are provided with the CALL statement. Please, make sure values are escaped correctly.

$mysqli = new mysqli("localhost", "root", "", "test"); if (!$mysqli-query("DROP TABLE IF EXISTS test") || !$mysqli-query("CREATE TABLE test(id INT)")) echo "Table creation failed: (" . $mysqli-errno . ") " . $mysqli-error; if (!$mysqli-query("DROP PROCEDURE IF EXISTS p") || !$mysqli-query("CREATE PROCEDURE p(IN id_val INT) BEGIN INSERT INTO test(id) VALUES(id_val); END;")) echo "Stored procedure creation failed: (" . $mysqli-errno . ") " . $mysqli-error; if (!$mysqli-query("CALL p(1)")) echo "CALL failed: (" . $mysqli-errno . ") " . $mysqli-error; if (!($res = $mysqli-query("SELECT id FROM test"))) echo "SELECT failed: (" . $mysqli-errno . ") " . $mysqli-error; var_dump($res-fetch_assoc());

array(1) { ["id"]= string(1) "1" }

INOUT/OUT parameter

The values of INOUT/OUT parameters are accessed using session variables.

$mysqli = new mysqli("localhost", "root", "", "test"); if (!$mysqli-query("DROP PROCEDURE IF EXISTS p") || !$mysqli-query('CREATE PROCEDURE p(OUT msg VARCHAR(50)) BEGIN SELECT "Hi!" INTO msg; END;')) echo "Stored procedure creation failed: (" . $mysqli-errno . ") " . $mysqli-error; if (!$mysqli-query("SET @msg = ''") || !$mysqli-query("CALL p(@msg)")) echo "CALL failed: (" . $mysqli-errno . ") " . $mysqli-error; if (!($res = $mysqli-query("SELECT @msg as _p_out"))) echo "Fetch failed: (" . $mysqli-errno . ") " . $mysqli-error; $row = $res-fetch_assoc(); echo $row['_p_out'];

Hi!

Application and framework developers may be able to provide a more convenient API using a mix of session variables and databased catalog inspection. However, please note the possible performance impact of a custom solution based on catalog inspection.

Handling result sets

Stored procedures can return result sets. Result sets returned from a stored procedure cannot be fetched correctly using mysqli_query(). The mysqli_query() function combines statement execution and fetching the first result set into a buffered result set, if any. However, there are additional stored procedure result sets hidden from the user which cause mysqli_query() to fail returning the user expected result sets.

Result sets returned from a stored procedure are fetched using mysqli_real_query() or mysqli_multi_query(). Both functions allow fetching any number of result sets returned by a statement, such as CALL. Failing to fetch all result sets returned by a stored procedure causes an error.

$mysqli = new mysqli("localhost", "root", "", "test"); if (!$mysqli-query("DROP TABLE IF EXISTS test") || !$mysqli-query("CREATE TABLE test(id INT)") || !$mysqli-query("INSERT INTO test(id) VALUES (1), (2), (3)")) echo "Table creation failed: (" . $mysqli-errno . ") " . $my

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