Question

I’m normalizing my database, to I’m trying to set the value of a field the same as the ID for that row so I can join tables.

I tried using LAST_INSERT_ID(), but it doesn’t work. I don’t get a error, but I only get zeros.

INSERT INTO `eleves` (`user_id`, 
`first_name`, `last_name`, 
`username`, `groupe`, 
`password`, `courriel`, 
`active`, `auteur`, 
`citations`, `absurde`, 
`vocabulaire`,  `analyse`, 
`themes`, `personnages`) 
VALUES (NULL, 
'Jane', 'Doe', 
'janedoe', '400', 
'password', '[e-mail]', 
'1', LAST_INSERT_ID(), 
LAST_INSERT_ID(), LAST_INSERT_ID(), 
LAST_INSERT_ID(), LAST_INSERT_ID(), 
LAST_INSERT_ID(), LAST_INSERT_ID());

Thanks!

Answer 1

It seems, during your MySQL session there happened no auto generated id was inserted. And hence for the fields for which you want to fill last_insert_id() must be a zero but not an empty(NULL?, SPACE?).

Try to define a primary key with auto increment in your table and let your generate a new record. And see what happens !

See the following example:

$ mysql -u ravi -p test
Enter password: ********
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2 to server version: 5.0.22-community-nt

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> select last_insert_id();
+------------------+
| last_insert_id() |
+------------------+
|                0 |
+------------------+
1 row in set (0.00 sec)

mysql> create table eleves( user_id int not null auto_increment primary key, username varchar(10), auteur int, citations int, absurde int );
Query OK, 0 rows affected (0.06 sec)

mysql> insert into eleves( username, auteur, citations, absurde )
    -> values( 'janedoe1', last_insert_id(), last_insert_id(), last_insert_id() );
Query OK, 1 row affected (0.03 sec)

mysql> select * from eleves;
+---------+----------+--------+-----------+---------+
| user_id | username | auteur | citations | absurde |
+---------+----------+--------+-----------+---------+
|       1 | janedoe1 |      0 |         0 |       0 |
+---------+----------+--------+-----------+---------+
1 row in set (0.00 sec)

mysql> select last_insert_id();
+------------------+
| last_insert_id() |
+------------------+
|                1 |
+------------------+
1 row in set (0.00 sec)

mysql> insert into eleves( username, auteur, citations, absurde )
    -> values( 'janedoe2', last_insert_id(), last_insert_id(), last_insert_id() );
Query OK, 1 row affected (0.01 sec)

mysql> select * from eleves;
+---------+----------+--------+-----------+---------+
| user_id | username | auteur | citations | absurde |
+---------+----------+--------+-----------+---------+
|       1 | janedoe1 |      0 |         0 |       0 |
|       2 | janedoe2 |      1 |         1 |       1 |
+---------+----------+--------+-----------+---------+
2 rows in set (0.00 sec)

mysql> select last_insert_id();
+------------------+
| last_insert_id() |
+------------------+
|                2 |
+------------------+
1 row in set (0.00 sec)

mysql>