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Case sql nested register

I am having trouble writing a case query in SQL. My first question is: is it possible to write an if statement below as a case statement in SQL Query in a select statement?

If not, then please take a look at the case example below and help / advise me to enter a valid format. Thanks and appreciated!

IF (var1 = 1){
do this1;
IF (var 1 = 2){
    Do this2;
    }Else{ 
    do something else1;
    }
Else if (Var 1 = 3){
    Do this3; 
    }Else{ 
    Do something else2;
    }

Here is my case study. I know this does not work because it is not a valid case argument. Maybe someone kindly helped me make this a valid expression. Thanks in advance.

    SELECT
CASE
    WHEN apple.type = 1 OR apple.type = 2
    THEN basket.S1
    ELSE 
        CASE 
            WHEN apple.type = 0 AND basket.S2 is null
            THEN basket.S1
            ELSE basket.S2  
        ELSE 
            CASE
                WHEN apple.type = 3 and basket.s3 is null
                THEN basket.S1
                ELSE basket.S3
            END
        END
    END 
FROM .....
WHERE .....
+4
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2 answers

Since you are checking for NULL values ​​and replacing non-zero values, you can make the query shorter using the function COALESCE.

SELECT
  CASE
    WHEN apple.type IN (1, 2) THEN basket.s1
    WHEN apple.type = 0 THEN COALESCE(basket.s2, basket.s1)
    WHEN apple.type = 3 THEN COALESCE(basket.s3, basket.s1)
  END
FROM ...
+2
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, , , , , ,

- ....

SELECT CASE 
           WHEN @Var1 = 1 THEN 'Something 1'
           WHEN @Var1 = 2 THEN 'Something 2'
           WHEN @Var1 = 3 THEN 'Something 3'
           ELSE 'Something Else'
       END 
FROM .....
WHERE .....

, , - ...

SELECT
    CASE
        WHEN apple.[type] IN (1,2)
        THEN basket.S1
        WHEN apple.type = 0 AND basket.S2 is null
        THEN basket.S1
        WHEN apple.type = 3 and basket.s3 is null
        THEN basket.S1
        ELSE basket.S3
    END
+3

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