mysql round()函数以及convert()函数，保留n位小数

mysql> select round(2.232,2);
+----------------+
| round(2.232,2) |
+----------------+
|           2.23 |
+----------------+
1 row in set (0.00 sec)



mysql> select convert(1.2323,decimal(6,2));
+------------------------------+
| convert(1.2323,decimal(6,2)) |
+------------------------------+
|                         1.23 |
+------------------------------+
1 row in set (0.00 sec)