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:
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
- mysqli::query
- mysqli::multi_query
- mysqli::next_result
- mysqli::more_results