ROUND

description

Syntax

T round(T x[, d]) 将x四舍五入后保留d位小数，d默认为0。如果d为负数，则小数点左边d位为0。如果x或d为null，返回null。 2.5会舍入到3，如果想要舍入到2的算法，请使用round_bankers函数。

如果 d 为一个列，并且第一个参数为 Decimal 类型，那么结果 Decimal 会跟入参 Decimal 具有相同的小数部分长度。

:::tip 该函数的另一个别名为 dround。 :::

example

mysql> select round(2.4);
+------------+
| round(2.4) |
+------------+
|          2 |
+------------+
mysql> select round(2.5);
+------------+
| round(2.5) |
+------------+
|          3 |
+------------+
mysql> select round(-3.4);
+-------------+
| round(-3.4) |
+-------------+
|          -3 |
+-------------+
mysql> select round(-3.5);
+-------------+
| round(-3.5) |
+-------------+
|          -4 |
+-------------+
mysql> select round(1667.2725, 2);
+---------------------+
| round(1667.2725, 2) |
+---------------------+
|             1667.27 |
+---------------------+
mysql> select round(1667.2725, -2);
+----------------------+
| round(1667.2725, -2) |
+----------------------+
|                 1700 |
+----------------------+
mysql> SELECT number
    -> , round(number * 2.5, number - 1) AS r_decimal_column
    -> , round(number * 2.5, 0) AS r_decimal_literal
    -> , round(cast(number * 2.5 AS DOUBLE), number - 1) AS r_double_column
    -> , round(cast(number * 2.5 AS DOUBLE), 0) AS r_double_literal
    -> FROM test_enhanced_round
    -> WHERE rid = 1;
+--------+------------------+-------------------+-----------------+------------------+
| number | r_decimal_column | r_decimal_literal | r_double_column | r_double_literal |
+--------+------------------+-------------------+-----------------+------------------+
|      1 |              3.0 |                 3 |               3 |                3 |
+--------+------------------+-------------------+-----------------+------------------+

keywords

ROUND, DROUND

RANDOM ROUND_BANKERS