Truncate (not round) decimal places in SQL Server

ROUND ( 123.456 , 2 , 1 )

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

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'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

Round has an optional parameter

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

This will remove the decimal part of any number

SELECT ROUND(@val,0,1)