Question

I’ve simplified my example here massively, so please excuse it if it looks to simple for what I’m trying to solve.

Is it possible to turn BETWEEN, into a NOT BETWEEN depending on a row value (i’ve used a variable here for simplicity), without duplicating the between statement?

I understand the use of case statements and boolean logic to help make static sql more “dynamic”, but I can’t seem to figure out a way for operators like BETWEEN.

Perhaps using some clever bitwise operation?

I have some set based SQL in development that is becoming difficult to manage already, so I’m hoping to simplify it by avoiding duplication.

I’m trying to do it in a SET based way, avoiding UDF’s if possible.

DECLARE @is int
set @is = 1

DECLARE @TestTable TABLE
(
    Name varchar(100),
    DOB datetime
)

INSERT INTO @TestTable(Name, DOB)
SELECT 'bob', '2011-08-18 10:10:10.100' UNION ALL
SELECT 'fred', '2014-08-18 10:10:10.100'


SELECT Name, DOB
FROM @TestTable
WHERE
    (@is = 1) AND (DOB BETWEEN '2011-08-18' AND '2012-08-18') 
    OR
    (@is = 0) AND (DOB NOT BETWEEN '2011-08-18' AND '2012-08-18')

So in the example above, if @is = 1, then bob is returned.
If @is = 0, then fred is returned.

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EDIT:
To clarify, the above statement works fine, but I’m attempting to optimise it to avoid having to write 2 BETWEEN statements. I wish to flip the logic depending on the value of @is…. somewhere using is to put in the NOT.

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EDIT 2:

Please see below for some pseudo code for what I’m trying to achieve. It’s pseudo, as t-SQL doesn’t allow “NOT” to be “injected” in the code in a set based operation like this (I’m trying to avoid stringy-dynamic sql).

SELECT Name, DOB
FROM @TestTable
WHERE
(
    DOB
        CASE @is
            WHEN 0
            THEN NOT ---pseudo code, this won't actually work, but gives an idea of what I'm trying to achieve.
        END
    BETWEEN '2011-08-18' AND '2012-08-18'
) 

Answer 1

I think you just need more parens…

WHERE
    (   (@is = 1) AND (DOB BETWEEN '2011-08-18' AND '2012-08-18')   )
    OR
    (   (@is = 0) AND (DOB NOT BETWEEN '2011-08-18' AND '2012-08-18')   )

EDIT

Got it — so then something like this:

WHERE @is = CASE WHEN DOB BETWEEN '2011-08-18' AND '2012-08-18' THEN 1 ELSE 0 END