How do I return values on the required column in the final table as below

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Current data:

| Old_code | New_code |
| -------- | -------- |
| HBP112 | HBP0501 |
| HBP112 | NULL |
| HBP132 | HBP0501 |
| HBP132 | NULL |
| HCIH112 | NULL |
| HCIH112 |HCIH0501 |

Required output:

| Old_code | New_code | Required Code|
-------- | -------- | ----------------|
| HBP112 | HBP0501 | HBP0501 | |
| HBP112 | NULL | HBP0501 |
| HBP132 | HBP0501 | HBP0501 |
| HBP132 | NULL | HBP0501 |
| HCIH112 | NULL | HCIH0501 |
| HCIH112 |HCIH0501 | HCIH0501 |

What I have tried:

select *, Max(new_code) over(partition by old_code) Required_code
from t;

i am still getting null values in result

Posted 1-Aug-23 23:53pm

yande mwale

Updated 2-Aug-23 0:09am

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Member 15627495 2-Aug-23 6:18am

when you use MAX(column_A) , you have to add "group by column_A"

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Richard Deeming · Answer 1 · 2023-08-02T00:09:00

Solution 1

You're nearly there:

SQL

SELECT
    Old_Code,
    New_Code,
    IsNull(MAX(New_Code) OVER (PARTITION BY Old_Code), Old_Code) As Required_Code
FROM
    t
;

Posted 2-Aug-23 0:09am

Richard Deeming