The Ultimate Guide to High Availability with MariaDB

LAST_INSERT_ID

Syntax

LAST_INSERT_ID(), LAST_INSERT_ID(expr)

Contents

  1. Syntax
  2. Description
  3. Examples
  4. See Also

Description

LAST_INSERT_ID() (no arguments) returns the first automatically generated value successfully inserted for an AUTO_INCREMENT column as a result of the most recently executed INSERT statement. The value of LAST_INSERT_ID() remains unchanged if no rows are successfully inserted.

If one gives an argument to LAST_INSERT_ID(), then it will return the value of the expression and the next call to LAST_INSERT_ID() will return the same value. The value will also be sent to the client and can be accessed by the mysql_insert_id function.

For example, after inserting a row that generates an AUTO_INCREMENT value, you can get the value like this:

SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                9 |
+------------------+

You can also use LAST_INSERT_ID() to delete the last inserted row:

DELETE FROM product WHERE id = LAST_INSERT_ID();

If no rows were successfully inserted, LAST_INSERT_ID() returns 0.

One can also use INSERT...RETURNING for this purpose.

The value of LAST_INSERT_ID() will be consistent across all versions if all rows in the INSERT or UPDATE statement were successful.

The currently executing statement does not affect the value of LAST_INSERT_ID(). Suppose that you generate an AUTO_INCREMENT value with one statement, and then refer to LAST_INSERT_ID() in a multiple-row INSERT statement that inserts rows into a table with its own AUTO_INCREMENT column. The value of LAST_INSERT_ID() will remain stable in the second statement; its value for the second and later rows is not affected by the earlier row insertions. (However, if you mix references to LAST_INSERT_ID() and LAST_INSERT_ID(expr), the effect is undefined.)

If the previous statement returned an error, the value of LAST_INSERT_ID() is undefined. For transactional tables, if the statement is rolled back due to an error, the value of LAST_INSERT_ID() is left undefined. For manual ROLLBACK, the value of LAST_INSERT_ID() is not restored to that before the transaction; it remains as it was at the point of the ROLLBACK.

Within the body of a stored routine (procedure or function) or a trigger, the value of LAST_INSERT_ID() changes the same way as for statements executed outside the body of these kinds of objects. The effect of a stored routine or trigger upon the value of LAST_INSERT_ID() that is seen by following statements depends on the kind of routine:

  • If a stored procedure executes statements that change the value of LAST_INSERT_ID(), the new value will be seen by statements that follow the procedure call.
  • For stored functions and triggers that change the value, the value is restored when the function or trigger ends, so following statements will not see a changed value.

Examples

CREATE TABLE t (
  id INTEGER UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
  f VARCHAR(1)) 
ENGINE = InnoDB;

INSERT INTO t(f) VALUES('a');

SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                1 |
+------------------+

INSERT INTO t(f) VALUES('b');

INSERT INTO t(f) VALUES('c');

SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                3 |
+------------------+

INSERT INTO t(f) VALUES('d'),('e');

SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                4 |
+------------------+

SELECT * FROM t;
+----+------+
| id | f    |
+----+------+
|  1 | a    |
|  2 | b    |
|  3 | c    |
|  4 | d    |
|  5 | e    |
+----+------+

SELECT LAST_INSERT_ID(12);
+--------------------+
| LAST_INSERT_ID(12) |
+--------------------+
|                 12 |
+--------------------+

SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|               12 |
+------------------+

INSERT INTO t(f) VALUES('f');

SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                6 |
+------------------+

SELECT * FROM t;
+----+------+
| id | f    |
+----+------+
|  1 | a    |
|  2 | b    |
|  3 | c    |
|  4 | d    |
|  5 | e    |
|  6 | f    |
+----+------+

SELECT LAST_INSERT_ID(12);
+--------------------+
| LAST_INSERT_ID(12) |
+--------------------+
|                 12 |
+--------------------+

INSERT INTO t(f) VALUES('g');

SELECT * FROM t;
+----+------+
| id | f    |
+----+------+
|  1 | a    |
|  2 | b    |
|  3 | c    |
|  4 | d    |
|  5 | e    |
|  6 | f    |
|  7 | g    |
+----+------+

See Also

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