在以下查询中，如何在where子句中使用“ group”进行比较？

Question

SELECT *,
    (SELECT name FROM oc_filter_group_description fgd
     WHERE f.filter_group_id = fgd.filter_group_id AND
           fgd.language_id = '1' ) AS `group`
FROM oc_filter f
LEFT JOIN oc_filter_description fd
    ON (f.filter_id = fd.filter_id)
WHERE fd.language_id = '1' AND fd.name LIKE '%FAB%'

Answer 1

You can rewrite your query so that it does not use any correlated subqueries in the select clause, but rather only joins:

SELECT f.*, fgd.name, fd.*
FROM oc_filter f
LEFT JOIN oc_filter_group_description fgd
    ON f.filter_group_id = fgd.filter_group_id AND
       fgd.language_id = '1'
LEFT JOIN oc_filter_description fd
    ON f.filter_id = fd.filter_id
WHERE
    fd.language_id = '1' AND
    fd.name LIKE '%FAB%' AND
    -- fgd.name = 'some name'

This approach makes the name column directly accessible in the WHERE clause. If you want to keep your current approach, then MySQL offers an option via the HAVING clause, where aliased items in the select clause can be directly used:

SELECT *,
    (SELECT name FROM oc_filter_group_description fgd
     WHERE f.filter_group_id = fgd.filter_group_id AND
           fgd.language_id = '1' ) AS `group`
FROM oc_filter f
LEFT JOIN oc_filter_description fd
    ON (f.filter_id = fd.filter_id)
WHERE fd.language_id = '1' AND fd.name LIKE '%FAB%'
HAVING `group` = 'some name';

The HAVING clause in MySQL, when GROUP BY does not appear, sort of functions as an overloaded WHERE clause, and aliases are available for use.