[英]Subquery with LIMIT in MYSQL complex query
我正在使用的Mysql版本不要让我在子查询中使用LIMIT,这样我可以加快查询速度。 在下一个查询中如何使用联接?
SELECT p . * , (
SELECT AVG( review_rating ) AS rating_total
FROM reviews r
WHERE r.review_item_ref = p.pattern_ref
AND r.review_state =1
GROUP BY r.review_item_ref
) AS review_rating
FROM patterns p
WHERE pattern_active >=0
AND p.pattern_family =27
AND p.pattern_ref
IN (
SELECT item_pattern_ref
FROM items
WHERE item_pattern_ref = p.pattern_ref LIMIT 1
)
GROUP BY p.pattern_id
ORDER BY p.pattern_description ASC , LCASE( p.pattern_description ) ASC
LIMIT 0 , 16
看起来您正在尝试验证p.pattern_ref在项目中是否匹配,对吗?
如果是这样的话,
SELECT
p . *,
(SELECT AVG( review_rating ) AS rating_total
FROM reviews r
WHERE r.review_item_ref = p.pattern_ref
AND r.review_state =1
GROUP BY r.review_item_ref
) AS review_rating
FROM patterns p
INNER JOIN items i ON p.pattern_ref = i.item_pattern_ref
WHERE p.pattern_active >= 0
AND p.pattern_family = 27
GROUP BY p.pattern_id
ORDER BY p.pattern_description ASC , LCASE( p.pattern_description ) ASC
LIMIT 0 , 16
应该管用。 INNER JOIN仅返回双方都匹配的行。
您不能在子查询中使用LIMIT。
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