查询一:
SELECT a.name,a.id
FROM name_list AS a
WHERE a.created_time BETWEEN "2013-03-14 00:00:00" AND "2013-03-14 23:59:59"
查询 2:
SELECT address_nr
FROM address_list
WHERE user_id="1117770"
LIMIT 1
要执行查询 1 和 2,我只需要 0.003 秒。但是当我将它们组合起来并将第二个查询作为子查询时,如下所示:
SELECT a.name,a.id,(SELECT address_nr FROM address_list WHERE user_id=a.id LIMIT 1) as 'address'
FROM name_list AS a
WHERE a.created_time BETWEEN "2013-03-14 00:00:00" AND "2013-03-14 23:59:59"
我需要 1 秒来执行它。当我检索数千个数据时,它需要数千秒。
有人可以指导我吗?谢谢!