在 SQL Server 中截断（非舍入）小数位

Question

I'm trying to determine the best way to truncate or drop extra decimal places in SQL without rounding. For example:

declare @value decimal(18,2)

set @value = 123.456

This will automatically round @value to be 123.46 , which is good in most cases. However, for this project, I don't need that. Is there a simple way to truncate the decimals I don't need? I know I can use the left() function and convert back to a decimal. Are there any other ways?

Answer 1

ROUND ( 123.456 , 2 , 1 )

When the third parameter != 0 it truncates rather than rounds

http://msdn.microsoft.com/en-us/library/ms175003(SQL.90).aspx

Syntax

ROUND ( numeric_expression , length [ ,function ] )

Arguments

• numeric_expression Is an expression of the exact numeric or approximate numeric data type category, except for the bit data type.

• length Is the precision to which numeric_expression is to be rounded. length must be an expression of type tinyint, smallint, or int. When length is a positive number, numeric_expression is rounded to the number of decimal positions specified by length. When length is a negative number, numeric_expression is rounded on the left side of the decimal point, as specified by length.

• function Is the type of operation to perform. function must be tinyint, smallint, or int. When function is omitted or has a value of 0 (default), numeric_expression is rounded. When a value other than 0 is specified, numeric_expression is truncated.

Answer 2

select round(123.456, 2, 1)

Answer 3

SELECT Cast(Round(123.456,2,1) as decimal(18,2))

Answer 4

实际上，无论第三个参数是 0 或 1 还是 2，它都不会舍入您的值。

CAST(ROUND(10.0055,2,0) AS NUMERIC(10,2))

Answer 5

Here's the way I was able to truncate and not round:

select 100.0019-(100.0019%.001)

returns 100.0010

And your example:

select 123.456-(123.456%.001)

returns 123.450

Now if you want to get rid of the ending zero, simply cast it:

select cast((123.456-(123.456%.001)) as decimal (18,2))

returns 123.45

Answer 6

Do you want the decimal or not?

If not, use

select ceiling(@value),floor(@value)

If you do it with 0 then do a round:

select round(@value,2)

Answer 7

Round has an optional parameter

Select round(123.456, 2, 1)  will = 123.45
Select round(123.456, 2, 0)  will = 123.46

Answer 8

Another truncate with no rounding solution and example.

    Convert 71.950005666 to a single decimal place number (71.9)
    1) 71.950005666 * 10.0 = 719.50005666
    2) Floor(719.50005666) = 719.0
    3) 719.0 / 10.0 = 71.9

    select Floor(71.950005666 * 10.0) / 10.0

Answer 9

这将删除任何数字的小数部分

SELECT ROUND(@val,0,1)

Answer 10

SELECT CAST(Value as Decimal(10,2)) FROM TABLE_NAME;

Would give you 2 values after the decimal point. (MS SQL SERVER)

Answer 11

Another way is ODBC TRUNCATE function:

DECLARE @value DECIMAL(18,3) =123.456;

SELECT @value AS val, {fn TRUNCATE(@value, 2)} AS result

LiveDemo

Output:

╔═════════╦═════════╗
║   val   ║ result  ║
╠═════════╬═════════╣
║ 123,456 ║ 123,450 ║
╚═════════╩═════════╝

Remark:

I recommend using built-in ROUND function with 3rd parameter set to 1.

Answer 12

I know this is pretty late but I don't see it as an answer and have been using this trick for years.

Simply subtract .005 from your value and use Round(@num,2).

Your example:

declare @num decimal(9,5) = 123.456

select round(@num-.005,2)

returns 123.45

It will automatically adjust the rounding to the correct value you are looking for.

By the way, are you recreating the program from the movie Office Space?

Answer 13

像这样尝试：

SELECT cast(round(123.456,2,1) as decimal(18,2)) 

Answer 14

Please try to use this code for converting 3 decimal values after a point into 2 decimal places:

declare @val decimal (8, 2)
select @val = 123.456
select @val =  @val

select @val

The output is 123.46

Answer 15

I think you want only the decimal value, in this case you can use the following:

declare @val decimal (8, 3)
SET @val = 123.456

SELECT @val - ROUND(@val,0,1)

Answer 16

I know this question is really old but nobody used sub-strings to round. This as advantage the ability to round really long numbers (limit of your string in SQL server which is usually 8000 characters):

SUBSTRING('123.456', 1, CHARINDEX('.', '123.456') + 2)

Answer 17

I think we can go much easier with simpler example solution found in Hackerrank:

Problem statement: Query the greatest value of the Northern Latitudes (LAT_N) from STATION that is less than 137.2345. Truncate your answer to 4 decimal places.

SELECT TRUNCATE(MAX(LAT_N),4)
FROM STATION
WHERE LAT_N < 137.23453;

Solution Above gives you idea how to simply make value limited to 4 decimal points. If you want to lower or upper the numbers after decimal, just change 4 to whatever you want.

Answer 18

ROUND(number, decimals, operation)

number => Required. The number to be rounded
decimals => Required. The number of decimal places to round number to
operation => Optional. If 0, it rounds the result to the number of decimal. If another value than 0, it truncates the result to the number of decimals. Default value is 0

SELECT ROUND(235.415, 2, 1)

will give you 235.410

SELECT ROUND(235.415, 0, 1)

will give you 235.000

But now trimming 0 you can use cast

SELECT CAST(ROUND(235.415, 0, 1) AS INT)

will give you 235

Answer 19

If you desire to take some number like 89.0904987 and turn it into 89.09 by simply omitting the undesired decimal places, simply use the following:

select cast(yourColumnName as decimal(18,2))

The following screenshot is from W3Schools SQL Data Types section, which describes what decimal(18,2) is doing:

Therefore,

select cast(89.0904987 as decimal(18,2))

gives you: 89.09

Answer 20

Mod(x,1)是我认为最简单的方法。

Answer 21

select convert(int,@value)