CODEWITHSUNDEEP
db2
Rintys
Rintys

Reputation: 19

Why didn't the query return any rows?

Why didn't the query return any rows?

SELECT 1 FROM sysibm.sysdummy1 WHERE 1 NOT IN (2, NULL)

Upvotes: 1

Views: 43

Answers (1)

Mark Barinstein
Mark Barinstein

Reputation: 12314

1 NOT IN (2, NULL) is equal to 1 <> 2 AND 1 <> NULL
The result of 1 <> NULL is UNKNOWN, so, the result of the original expression is:
TRUE AND UNKNOWN which is UNKNOWN.
But you get the result for rows, where an expression in WHERE evaluates as TRUE only.

Upvotes: 1

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