TRUNCATE(X,D) returns the number X, truncated to D decimal places. : TRUNCATE « Math Numeric Functions « MySQL Tutorial

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

If D is 0, the result has no decimal point or fractional part.

D can be negative to cause D digits left of the decimal point of the value X to become zero.

mysql>
mysql> SELECT TRUNCATE(1.223,1);
+-------------------+
| TRUNCATE(1.223,1) |
+-------------------+
|               1.2 |
+-------------------+
1 row in set (0.00 sec)

mysql>
mysql> SELECT TRUNCATE(1.999,1);
+-------------------+
| TRUNCATE(1.999,1) |
+-------------------+
|               1.9 |
+-------------------+
1 row in set (0.00 sec)

mysql>