Question

I have the following @temp table :

SELECT * 
FROM @temp
WHERE LinkingID = 1

------------------------------------------------------------------
|Condition_ID   LinkingID   Operator   Variable1    Variable2    |
|     1             1          ==        25             2        |
|     2             1          <>        3              7        |
|     3             1          ==        4              4        |
------------------------------------------------------------------

I want to implement a CASE ( ??? ) that will check if Variable1 OPERATOR Variable2 is true, make the check for all rows and IF all rows are true then do something, else break off and abort.

I was thinking something like this ( I’m not sure how to express this in T-SQL so I use pseudolanguage ) :

CASE 
    WHEN Operator LIKE '=='
        THEN IF Variable1 == Variable2 THEN TRUE
        ELSE THEN FALSE
    WHEN Operator LIKE '<>'
        THEN IF Variable1  <> Variable2 THEN TRUE
        ELSE THEN FALSE
FROM @temp

If the result of this is true for all rows, then do something, else do something else

In the scenario above :
Row1 would return FALSE
Row2 would return TRUE
Row3 would return TRUE

Hence the result is FALSE.

Answer 1

Accumulating comparison results over the whole table

Checking that the whole table returns true for all rows is best done to count false ones and check whether that number is greater equal to 0. If it’s 0 then it means that all rows matched otherwise number indicates number of rows that failed

Mind the inverted comparison compared to Operator value to catch negatives:

declare @NonMatched int

select
    @NonMatched = sum(
        case
            when [Operator] = '==' and Variable1 <> Variable2 then 1
            when [Operator] = '<>' and Variable1 = Variable2 then 1
            else 0
        end
    )
from @temp
where LinkingID = 1

if @NonMatched = 0
begin
    -- execute your stored procedure or whatever else set of statements
end

Here’s also a SQLFiddle that’s based on upper code.