How do I use alias in where clause? [duplicate]

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The SQL-Server docs says:

column_alias can be used in an ORDER BY clause, but it cannot be used in a WHERE, GROUP BY, or HAVING clause.

Similar in the MySQL doc it says:

Standard SQL disallows references to column aliases in a WHERE clause. This restriction is imposed because when the WHERE clause is evaluated, the column value may not yet have been determined.

In MySQL you can at least reuse aliases in the SELECT clause

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