FLOOR(X) returns the largest integer value not greater than X. : FLOOR « Math Numeric Functions « MySQL Tutorial

1. MySQL Tutorial
2. Math Numeric Functions
3. FLOOR

mysql>
mysql> SELECT FLOOR(1.23);
+-------------+
| FLOOR(1.23) |
+-------------+
|           1 |
+-------------+
1 row in set (0.00 sec)

mysql> SELECT FLOOR(-1.23);
+--------------+
| FLOOR(-1.23) |
+--------------+
|           -2 |
+--------------+
1 row in set (0.02 sec)

mysql>