Home > database >  Excluding Records using specific conditions
Excluding Records using specific conditions

Time:06-02

I have a table as below

ID Type Part
CD1 Service A
CD1 Service null
CD1 Service B
CD1 Sales A
CD2 Service null
CD2 Sales B
CD3 Service A
CD3 Service null

Output Required:

ID Type Part
CD1 Service A
CD1 Service B
CD1 Sales A
CD2 Service null
CD2 Sales B
CD3 Service A

Explanation : For example CD1 has Service as Type with A,B and a null as Part, CD2 has Service as Type with only null as Part. Since CD1 has A,B as part, null value record has to be excluded and CD2 with Service as Type doesn't contain any values other than null it should not be excluded.

Similarly CD3 has Service as Type with A and null as Part. Since A exists null value record has to be excluded.

Is this possible to achieve using SQL?

Thanks in Advance

CodePudding user response:

You can assign a ranking using the ROW_NUMBER window function, where the null values will be assigned the least value. Then you can select all rows from your table where the value is not null or the ranking is 1 (if null is found in first position, it will mean that it's the only value for that combination of ID and Type):

WITH cte AS (
    SELECT *, 
           ROW_NUMBER() OVER(PARTITION BY ID, Type 
                             ORDER     BY Part DESC) AS rn
    FROM tab
)
SELECT ID,
       Type, 
       Part
FROM cte
WHERE Part IS NOT NULL 
   OR rn = 1

Try it here.

  • Related