Stored Procedures

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, depending on the MySQL version. 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.

Example #1 Calling a stored procedure

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("example.com", "user", "password", "database");

$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");

$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;");

$mysqli->query("CALL p(1)");

$result = $mysqli->query("SELECT id FROM test");

var_dump($result->fetch_assoc());

The above example will output:

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

INOUT/OUT parameter

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

Example #2 Using session variables

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("example.com", "user", "password", "database");

$mysqli->query("DROP PROCEDURE IF EXISTS p");
$mysqli->query('CREATE PROCEDURE p(OUT msg VARCHAR(50)) BEGIN SELECT "Hi!" INTO msg; END;');

$mysqli->query("SET @msg = ''");
$mysqli->query("CALL p(@msg)");

$result = $mysqli->query("SELECT @msg as _p_out");

$row = $result->fetch_assoc();
echo $row['_p_out'];

The above example will output:

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.

Example #3 Fetching results from stored procedures

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("example.com", "user", "password", "database");

$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

$mysqli->query("DROP PROCEDURE IF EXISTS p");
$mysqli->query('CREATE PROCEDURE p() READS SQL DATA BEGIN SELECT id FROM test; SELECT id + 1 FROM test; END;');

$mysqli->multi_query("CALL p()");

do {
    if ($result = $mysqli->store_result()) {
        printf("---\n");
        var_dump($result->fetch_all());
        $result->free();
    }
} while ($mysqli->next_result());

The above example will output:

---
array(3) {
  [0]=>
  array(1) {
    [0]=>
    string(1) "1"
  }
  [1]=>
  array(1) {
    [0]=>
    string(1) "2"
  }
  [2]=>
  array(1) {
    [0]=>
    string(1) "3"
  }
}
---
array(3) {
  [0]=>
  array(1) {
    [0]=>
    string(1) "2"
  }
  [1]=>
  array(1) {
    [0]=>
    string(1) "3"
  }
  [2]=>
  array(1) {
    [0]=>
    string(1) "4"
  }
}

Use of prepared statements

No special handling is required when using the prepared statement interface for fetching results from the same stored procedure as above. The prepared statement and non-prepared statement interfaces are similar. Please note, that not every MYSQL server version may support preparing the CALL SQL statement.

Example #4 Stored Procedures and Prepared Statements

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("example.com", "user", "password", "database");

$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

$mysqli->query("DROP PROCEDURE IF EXISTS p");
$mysqli->query('CREATE PROCEDURE p() READS SQL DATA BEGIN SELECT id FROM test; SELECT id + 1 FROM test; END;');

$stmt = $mysqli->prepare("CALL p()");

$stmt->execute();

do {
    if ($result = $stmt->get_result()) {
        printf("---\n");
        var_dump($result->fetch_all());
        $result->free();
    }
} while ($stmt->next_result());

The above example will output:

---
array(3) {
  [0]=>
  array(1) {
    [0]=>
    int(1)
  }
  [1]=>
  array(1) {
    [0]=>
    int(2)
  }
  [2]=>
  array(1) {
    [0]=>
    int(3)
  }
}
---
array(3) {
  [0]=>
  array(1) {
    [0]=>
    int(2)
  }
  [1]=>
  array(1) {
    [0]=>
    int(3)
  }
  [2]=>
  array(1) {
    [0]=>
    int(4)
  }
}

Of course, use of the bind API for fetching is supported as well.

Example #5 Stored Procedures and Prepared Statements using bind API

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("example.com", "user", "password", "database");

$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

$mysqli->query("DROP PROCEDURE IF EXISTS p");
$mysqli->query('CREATE PROCEDURE p() READS SQL DATA BEGIN SELECT id FROM test; SELECT id + 1 FROM test; END;');

$stmt = $mysqli->prepare("CALL p()");

$stmt->execute();

do {
    if ($stmt->store_result()) {
        $stmt->bind_result($id_out);
        while ($stmt->fetch()) {
            echo "id = $id_out\n";
        }
    }
} while ($stmt->next_result());

The above example will output:

id = 1
id = 2
id = 3
id = 2
id = 3
id = 4

See also