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I have a subquery which can return multiple results if a customer has duplicated sales codes.

I currently LIMIT 1 to just return the most recent but ... Is there away to return NULL or "DUPLICATE" if RESULT > 1?

I am using this field to overwrite a field which already has a default - therefore, I would just prefer to use the default or raise an alert for rectification.

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  • if a customer has duplicated sales codes. This is practically equal to "My data is inconsistent, but I don't want to purify my data and do something to prevent this in future". It's bad... It is necessary to treat the disease and not its symptoms. I'd recommend you: 1) remove duplicates; 2) create unique index which prevents duplicates.
    – Akina
    Commented Mar 22, 2019 at 5:02
  • Did you read the OP - "I would just prefer to use the default or raise an alert for rectification."
    – php-b-grader
    Commented Mar 24, 2019 at 21:59

1 Answer 1

Reset to default
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You could try something like this, add a select case to your subquery

select (select case when (select count(*) from subquery) >1 then 'duplicate' else 'not duplicate' end)

Though I'm not sure if I would recommend that, but there is one method.

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