For UNION , INTERSECT and EXCEPT , when are two SELECT results union compatible in PostgreSQL?

Question

For  UNION ,  INTERSECT  and  EXCEPT , when are two  SELECT  results union compatible in PostgreSQL?

Accepted Answer

When they return the same number of columns with compatible data types.

Answer

When they select from the same tables.

Answer

When their column names are identical.

Answer

When they return the same number of rows.

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