Question

我有以下查询，虽然它有效但需要很长时间才能加载

SELECT name, t1.*
FROM user, driver_tracker t1 
LEFT JOIN driver_tracker t2
ON (t1.phone = t2.phone AND t1.id < t2.id)
WHERE user.phone = t1.phone
AND companyid = 'asus'
AND t2.id IS NULL
ORDER BY name

Answer 1

以下是您正确表达的查询：

SELECT u.name, t1.*
FROM user u JOIN
     driver_tracker t1 
     ON u.phone = t1.phone LEFT JOIN
     driver_tracker t2
     ON (t1.phone = t2.phone AND t1.id < t2.id)
WHERE u.companyid = 'asus' AND t2.id IS NULL
ORDER BY name;

（注意用适当的显式连接替换from子句中的逗号。简单规则：永远不要在from子句中使用逗号。）

推荐索引：user(companyid, phone, name)和driver_tracker(phone, id)。

MYSQL查询需要很长时间才能加载

1 个答案: