四舍五入与截断数字
SQL Server 中级
Ginger Grant
Instructor
在 T-SQL 中四舍五入
ROUND(number, length [,function])
在 T-SQL 中四舍五入
SELECT DurationSeconds,
ROUND(DurationSeconds, 0) AS RoundToZero,
ROUND(DurationSeconds, 1) AS RoundToOne
FROM Incidents
+--------------------+------------------+------------------+
|DurationSeconds |RoundToZero |RoundToOne |
+--------------------+------------------+------------------+
|121.6480 |122.0000 |121.6000 |
|170.3976 |170.0000 |170.4000 |
|336.0652 |336.0000 |336.1000 |
...
+--------------------+------------------+------------------+
小数点左侧的四舍五入
SELECT DurationSeconds,
ROUND(DurationSeconds, -1) AS RoundToTen,
ROUND(DurationSeconds, -2) AS RoundToHundred
FROM Incidents
+--------------------+------------------+------------------+
|DurationSeconds |RoundToTen |RoundToHundred |
+--------------------+------------------+------------------+
|121.6480 |120.0000 |100.0000 |
|170.3976 |170.0000 |200.0000 |
|336.0652 |340.0000 |300.0000 |
...
+--------------------+------------------+------------------+
截断数字
截断
17.85 $\rightarrow$ 17
四舍五入
17.85 $\rightarrow$ 18
用 ROUND() 截断
当指定第三个参数时，ROUND() 可用于截断值
ROUND(number, length [,function])
- 将第三个参数设为非零值
在 T-SQL 中截断
SELECT Profit,
ROUND(DurationSeconds, 0) AS RoundingtoWhole,
ROUND(DurationSeconds, 0, 1) AS Truncating
FROM Incidents
+--------------------+------------------+------------------+
|Profit |RoundingtoWhole |Truncating |
+--------------------+------------------+------------------+
|15.6100 |16.0000 |15.0000 |
|13.2444 |13.0000 |13.0000 |
|17.9260 |18.0000 |17.0000 |
...
+--------------------+------------------+------------------+
截断会在指定位数后直接去掉所有数字
Passons à la pratique !
SQL Server 中级
