Paste this into a new question or an answer at dba.stackexchange.com:
<!-- --> > select 'x' NOT IN ('a', 'b', NULL) > > <pre> > | 'x' NOT IN ('a', 'b', NULL) | > | --------------------------: | > | <em>null</em> | > </pre> *db<>fiddle [here](https://dbfiddle.uk/?rdbms=mysql_8.0&rdbms2=mysql_8.0&fiddle=111f1189011651c61f603fc7f69567a9)*
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