Is there a way to structure a WHERE statement to act like this pseudocode? Kind of like a nested WHERE statement?
SELECT
t.Val1
,t.Val2
,t.Val3
,t.Val4
,t.Val5
FROM table t
WHERE
IF t.Val1 = 'ABC'
THEN WHERE t.Val2 = t.Val3
ELSE
WHERE t.Val4 = t.Val5
Using MS SQL Server
Just use boolean logic:
WHERE (t.Val1 = 'ABC' AND t.Val2 = t.Val3) OR
(t.Val1 <> 'ABC' AND t.Val4 = t.Val5)
This formulation assumes that val1 is never NULL -- NULL values are easily handled, if necessary.
A third alternative to the other solutions would be IIF expressions.
DROP TABLE IF EXISTS #Test;
CREATE TABLE #Test
(
TestID TINYINT PRIMARY KEY
,Val1 VARCHAR(3)
,Val2 INT
,Val3 INT
,Val4 INT
,Val5 INT
)
;
GO
INSERT INTO #Test
VALUES
(1, 'ABC', 1, 1, 1, 2)
,(2, 'ABC', 1, 2, 2, 2)
,(3, 'XYZ', 1, 1, 1, 2)
,(4, 'XYZ', 1, 2, 2, 2)
;
SELECT
*
FROM #Test
WHERE IIF(Val1 = 'ABC', Val2, Val4) = IIF(Val1 = 'ABC', Val3, Val5)
;
you can use case statement instead of where condition. even you can to make computed column by case statement like the below link :
https://blog.sqlauthority.com/2016/04/27/sql-server-computed-column-conditions-case-statement/