parser: ensure NOT NOT EXISTS is the same as EXISTS (#1254) - Githubissues

pingcap / parser

A MySQL Compatible SQL Parser

Apache License 2.0

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parser: ensure NOT NOT EXISTS is the same as EXISTS (#1254) #1265

Closed kennytm closed 3 years ago

kennytm commented 3 years ago

Cherry-pick #1254 to release-5.0

What problem does this PR solve?

Fix #1251

What is changed and how it works?

When applying NOT to an ExistsSubqueryExpr, flip its Not flag instead of always setting it to true.

Check List

Tests

Unit test

Code changes

Side effects

Related changes

Need to cherry-pick to the release branch
Need to be included in the release note
- NOT NOT EXISTS (SELECT ...) is now correctly interpreted as EXISTS (SELECT ...).