Question

I noticed that if I prepare a multi-insert statement and execute it into MySQL via PDO, and then request the last_insert_id, I get the first ID of the multiple inserted rows, not the last one. Specifically:

"INSERT INTO test_table (value1, value2, value3) VALUES (1, 2, 3), (1, 2, 3)";

will create these rows on an empty table:

ID value1 value2 value3
1    1      2      3
2    1      2      3

But the last_insert_id will return “1”.
Is this a known issue or am I doing something wrong? Could someone verify/test/explain this? I am at a loss at what to do to get the proper last ID, save for doing an actual select which would be WAY slower.

Answer 1

It’s correct mysql behavior

http://dev.mysql.com/doc/refman/5.0/en/information-functions.html#function_last-insert-id

mysql> USE test;
Database changed
mysql> CREATE TABLE t (
    ->   id INT AUTO_INCREMENT NOT NULL PRIMARY KEY,
    ->   name VARCHAR(10) NOT NULL
    -> );
Query OK, 0 rows affected (0.09 sec)

mysql> INSERT INTO t VALUES (NULL, 'Bob');
Query OK, 1 row affected (0.01 sec)

mysql> SELECT * FROM t;
+----+------+
| id | name |
+----+------+
|  1 | Bob  |
+----+------+
1 row in set (0.01 sec)

mysql> SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                1 |
+------------------+
1 row in set (0.00 sec)

mysql> INSERT INTO t VALUES
    -> (NULL, 'Mary'), (NULL, 'Jane'), (NULL, 'Lisa');
Query OK, 3 rows affected (0.00 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM t;
+----+------+
| id | name |
+----+------+
|  1 | Bob  |
|  2 | Mary |
|  3 | Jane |
|  4 | Lisa |
+----+------+
4 rows in set (0.01 sec)

mysql> SELECT LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                2 |
+------------------+
1 row in set (0.00 sec)