How to define a function returning one of multiple data types?

Question

I have a function with a conditional result. Based on the argument value it should either return varchar or int or uuid or timestamp .

What should the return type of that function be?

Answer 1

SQL is strictly typed. The simple solution is to return one text field . Every value can be cast to text . (You might add a second return column holding the type name as meta information.)

Alternatively, return four typed fields (varchar, int, uuid, timestamp) , and only fill one of them, depending on the result.

A polymorphic function would only be an option if you can tell the return type at call time and pass typed input accordingly.

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