How to select null when the record does not exist with UNION ALL?

Towards an Error-free UNION ALL | dbt Developer Blog

Объединение UNION и UNION ALL в SQL – описание и примеры

sql injection "union select null" - CodeProject

Union select null, null, null, null, null, null, null from information_schema.tables. for a small database containing three tables. SELECT some columns FROM ATable WHERE AColumn=1 UNION SELECT ALL 1

SQL-инъекции' union select null, null, null -- / Хабр

SELECT INTO and non-nullable columns - Brent Ozar Unlimited

NULL Values In SQL | SQL UNION Clause - DataFlair

Union all query with null value in the first select clause, returns...

SQL UNION Operator

How the SQL UNION Operator Deals with NULL Values