Truncate (not round) decimal places in SQL Server

Solution 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.

select round(123.456, 2, 1)

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

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