使用Case Expression在带SQL的派生列中交叉应用

Question

I have very simple query with few computed column like

SELECT COL1 , COL2,COL3
COL4 = (COL1-(COL2*.15))
COL5 = (COL3*(COL1*1.5))

FROM TABLE1 AS A 
INNER JOIN TABLE2 AS B
ON A.ID = B.ID

Now i am trying to put Case statement on computed column value using cross apply

CROSS APPLY (

SELECT REMARKS = CASE WHEN COL4> COL1 THEN GOOD ELSE BAD END

but this is giving error .

In Output I am expecting all column ie col1,col2,col3,col4,col5,Remarks

Can someone please suggest what is my mistake?

Answer 1

The problem is that CROSS APPLY cannot access a computed field from the SELECT clause because it is evaluated first.

One option is to cascade your computed columns using one CROSS APPLY for each column:

SELECT COL1, COL2, COL3,
       C.COL4, D.COL5,
       E.REMARKS 
FROM TABLE1 AS A 
INNER JOIN TABLE2 AS B ON A.ID = B.ID
CROSS APPLY (SELECT COL4 = (COL1-(COL2*.15))) AS C
CROSS APPLY (SELECT COL5 = (COL3*(COL1*1.5))) AS D
CROSS APPLY (SELECT REMARKS = CASE WHEN C.COL4 > COL1 THEN 'GOOD' ELSE 'BAD' END) AS E

Demo here

Answer 2

What about this?

SELECT *,CASE WHEN COL4 > COL1 THEN 'GOOD' ELSE 'BAD' END AS Remark
FROM (
         SELECT COL1 , COL2,COL3
         COL4 = (COL1-(COL2*.15))
         COL5 = (COL3*(COL1*1.5))
         FROM TABLE1 AS A 
         INNER JOIN TABLE2 AS B ON A.ID = B.ID
)M

Answer 3

Enclose your first script in select statement then do cross apply

SELECT * FROM (SELECT COL1 , COL2,COL3
                ,COL4 = (COL1-(COL2*.15))
                ,COL5 = (COL3*(COL1*1.5)) 

FROM TABLE1 AS A 
INNER JOIN TABLE2 AS B
ON A.ID = B.ID )t

CROSS APPLY

(
SELECT  CASE WHEN t.COL4 > t.COL1 THEN 'GOOD' ELSE 'BAD' END REMARKS
) t1

Answer 4

Select x.Iss_Carat,x.Rec_Carat,x.REMARKS from Process_Issue_Receive PTR
cross apply( SELECT *, REMARKS = CASE WHEN Rec_Carat> Iss_Carat THEN 'GOOD' 
                                ELSE 'BAD' 
                                END FROM LAB_Issue_Receive LIR where ptr.Lot_Key = LIR.Lot_key)x where x.REMARKS = 'GOOD'

Try This Query with 2 Diff Table