此函式返回x舍入到最接近的整數。如果第二個引數，D有提供，則函式返回x四捨五入至第D位小數點。D必須是正數或全部右邊小數點的數位將被刪除。請看下面的例子：
mysql>SELECT ROUND(5.693893); +---------------------------------------------------------+ | ROUND(5.693893) | +---------------------------------------------------------+ | 6 | +---------------------------------------------------------+ 1 row in set (0.00 sec) mysql>SELECT ROUND(5.693893,2); +---------------------------------------------------------+ | ROUND(5.693893,2) | +---------------------------------------------------------+ | 5.69 | +---------------------------------------------------------+ 1 row in set (0.00 sec)