SQL Server round()

Question

I want to round value of one select

For example:

select width from Home

The result of width is "3.999999999999999"

I want to be "3.99" or "3.9"

Answer 1

ROUND(width, 1 or 2, 1) should work best for you. Example:

SELECT CONVERT(NUMERIC(13,2), ROUND(width, 2, 1))
FROM Home

will return 3.99, and

SELECT CONVERT(NUMERIC(13,1), ROUND(width, 1, 1))
FROM Home

will return 3.9

Answer 2

If you want a value of 3.99 or 3.9, then you do not want round() . You want floor() . However, that works on integers, but not decimals.

The naive method of cast(width as decimal(10,2)) will return 4.00 , as will round(width, 2) . One method is to subtract a small amount. So:

select cast(width - 0.005 as decimal(10, 2))

should give you "3.99".

Answer 3

If you need only two decimal values you can multiply by 100, floor the result and divide by 100 (This is necessary because floor works only flooring a number to an integer):

select floor(width * 100) / 100 from Home  

Here are the steps

3.99999999 * 100 = 399.999999    --- Multiply by 100
floor(399.999999) = 399          --- floor 
399 / 100 = 3.99                 --- Divide by 100

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It is also possible using a different form of round function with a third parameter .

When the third parameter is different from 0 the result is truncated instead of rounded

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.

Here is the select using this version of round :

 select round(width, 2, 1) from Home 

Answer 4

It's fairly simple, if you want the result 3.9 then

select round(width,1) from Home

If you need the result 3.99 then use..

select round(width,2) from Home