Auto increment a value on the fly with MySQL

SELECT with auto incrementing value

To have an auto incrementing value, first assign a variable like so:

SELECT @i:=0;

This can now be incremented in the SELECT query like so:

SELECT *, @i:=@i+1 AS i FROM fruit ORDER BY name;

This will return:

+----------+--------+-----------+------+
| fruit_id | name   | somevalue | i    |
+----------+--------+-----------+------+
|        4 | Apple  |         0 |    1 |
|        1 | Banana |         0 |    2 |
|        3 | Cherry |         0 |    3 |
|        2 | Orange |         0 |    4 |
+----------+--------+-----------+------+

Notice that for each record, i is one greater than the previous record.

UPDATE with auto incrementing value

The next example updates the "somevalue" column with an incrementing value. Note that @i needs to be reset otherwise it will continue in this example with 5 being the next number.

SELECT @i:=0;

As with the SELECT query above, we'll update ordering by name:

UPDATE fruit SET somevalue = @i:=@i+1 ORDER BY name;

And the result from "SELECT * FROM fruit"

+----------+--------+-----------+
| fruit_id | name   | somevalue |
+----------+--------+-----------+
|        1 | Banana |         2 |
|        2 | Orange |         4 |
|        3 | Cherry |         3 |
|        4 | Apple  |         1 |
+----------+--------+-----------+

or "SELECT * FROM fruit ORDER BY name"

+----------+--------+-----------+
| fruit_id | name   | somevalue |
+----------+--------+-----------+
|        4 | Apple  |         1 |
|        1 | Banana |         2 |
|        3 | Cherry |         3 |
|        2 | Orange |         4 |
+----------+--------+-----------+