PostgreSQL constraints for some fields

Question

I need all three fields in my table to be null at once, or all were not null. How to do it? Thanks.

user330315 · Accepted Answer · 2020-07-29 09:02:19Z

2

You need a check constraint

alter table your_table
   add constraint check_nulls
   check (num_nonnulls(col1, col2, col3) in (0,3));

num_nonnulls counts the number of not-null values passed to it. Your requirement is that either all of them are null (result = 0) or all of them are not null (result = 3)

answered Jul 29, 2020 at 9:02

user330315

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