Support for server-side prepared statements was added in MySQL 4.1. This support takes advantage of the efficient client/server binary protocol, provided that you use an appropriate client programming interface. Candidate interfaces include the MySQL C API client library (for C programs), MySQL Connector/J (for Java programs), and MySQL Connector/NET. For example, the C API provides a set of function calls that make up its prepared statement API. See Section 17.6.4, “C API Prepared Statements”. Other language interfaces can provide support for prepared statements that use the binary protocol by linking in the C client library, one example being the mysqli extension, available in PHP 5.0 and later.

Beginning with MySQL 4.1.3, an alternative SQL interface to prepared statements is available. This interface is not as efficient as using the binary protocol through a prepared statement API, but requires no programming because it is available directly at the SQL level:

SQL syntax for prepared statements is intended to be used for situations such as these:

SQL syntax for prepared statements is based on three SQL statements:

The following examples show two equivalent ways of preparing a statement that computes the hypotenuse of a triangle given the lengths of the two sides.

The first example shows how to create a prepared statement by using a string literal to supply the text of the statement:

mysql> PREPARE stmt1 FROM 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
mysql> SET @a = 3;
mysql> SET @b = 4;
mysql> EXECUTE stmt1 USING @a, @b;
+------------+
| hypotenuse |
+------------+
|          5 |
+------------+
mysql> DEALLOCATE PREPARE stmt1;

The second example is similar, but supplies the text of the statement as a user variable:

mysql> SET @s = 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
mysql> PREPARE stmt2 FROM @s;
mysql> SET @a = 6;
mysql> SET @b = 8;
mysql> EXECUTE stmt2 USING @a, @b;
+------------+
| hypotenuse |
+------------+
|         10 |
+------------+
mysql> DEALLOCATE PREPARE stmt2;

Here is an additional example which demonstrates how to choose the table on which to perform a query at run time, by storing the name of the table as a user variable:

mysql> USE test;
mysql> CREATE TABLE t1 (a INT NOT NULL);
mysql> INSERT INTO t1 VALUES (4), (8), (11), (32), (80);

mysql> SET @table = 't1';
mysql> SET @s = CONCAT('SELECT * FROM ', @table);

mysql> PREPARE stmt3 FROM @s;
mysql> EXECUTE stmt3;
+----+
| a  |
+----+
|  4 |
|  8 |
| 11 |
| 32 |
| 80 |
+----+

mysql> DEALLOCATE PREPARE stmt3;

A prepared statement is specific to the session in which it was created. If you terminate a session without deallocating a previously prepared statement, the server deallocates it automatically.

To guard against too many prepared statements being created simultaneously, set the max_prepared_stmt_count system variable. To prevent the use of prepared statements, set the value to 0.

The following SQL statements can be used in prepared statements: ALTER TABLE, COMMIT, CREATE INDEX, CREATE TABLE, DELETE, DO, DROP INDEX, DROP TABLE, INSERT, RENAME TABLE, REPLACE, SELECT, SET, UPDATE, and most SHOW statements. Other statements are not yet supported.

SQL syntax for prepared statements cannot be used in nested fashion. That is, a statement passed to PREPARE cannot itself be a PREPARE, EXECUTE, or DEALLOCATE PREPARE statement.

SQL syntax for prepared statements is distinct from using prepared statement API calls. For example, you cannot use the mysql_stmt_prepare() C API function to prepare a PREPARE, EXECUTE, or DEALLOCATE PREPARE statement.

SQL syntax for prepared statements does not support multi-statements (that is, multiple statements within a single string separated by “;” characters).