MySQL入门命令之函数-单行函数-数学函数

1、round—四舍五入

#默认情况下保留整数
mysql> select round(1.65);
+-------------+
| round(1.65) |
+-------------+
|           2 |
+-------------+
1 row in set (0.00 sec)

mysql> select round(-1.65);
+--------------+
| round(-1.65) |
+--------------+
|           -2 |
+--------------+
1 row in set (0.00 sec)
#保留指定的位数
mysql> select round(1.556,2);
+----------------+
| round(1.556,2) |
+----------------+
|           1.56 |
+----------------+
1 row in set (0.00 sec)

2、向上取整–返回大于等于该数的最小整数

mysql> select ceil(1.02);
+------------+
| ceil(1.02) |
+------------+
|          2 |
+------------+
1 row in set (0.00 sec)

mysql> select ceil(1.00);
+------------+
| ceil(1.00) |
+------------+
|          1 |
+------------+
1 row in set (0.00 sec)

3、floor 向下取整–返沪hi小于等于该数的最大整数

mysql> select floor(-1.02);
+--------------+
| floor(-1.02) |
+--------------+
|           -2 |
+--------------+
1 row in set (0.00 sec)

4、truncate 截断–去掉指定位数小数后的所有小数

mysql> select truncate(1.69,1);
+------------------+
| truncate(1.69,1) |
+------------------+
|              1.6 |
+------------------+
1 row in set (0.00 sec)

5、mod 取余

mysql> select mod(-11,3);
+------------+
| mod(-11,3) |
+------------+
|         -2 |
+------------+
1 row in set (0.00 sec)

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