mysql: ERROR 1054 (42S22): Unknown column ... in 'where clause'

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Using alias 'as'

Query:

SELECT field AS my_field FROM my_table WHERE my_field = 1;

would result in:

ERROR 1054 (42S22): Unknown column 'my_field' in 'where clause'

Aliases defined with AS can only be used with GROUP BY, ORDER BY, or HAVING.

Corrected SQL:

SELECT field AS my_field FROM my_table HAVING my_field = 1;