[英]Select from multiple tables without using join and union
我有以下 SQL 查询:
SELECT t1.id as id,
t1.username as username,
CONCAT_WS(' ', t2.ad,t2.soyad) as fullname,
t2.title as title,
t3.pass as password,
t3.phone_login as hat,
t2.time as date
FROM kullanici t1, kullanici_tanim t2, dial_users t3
WHERE t1.id = t2.usr_id AND t1.agent_id = t3.user_id
GROUP BY t1.id
ORDER BY t1.id ASC
此查询工作正常。 我想知道的是我应该使用连接吗? 什么是正确的方法?
对于符合 ANSI-92 的代码,请使用连接。 例如:
SELECT t1.id as id,
t1.username as username,
CONCAT_WS(' ', t2.ad,t2.soyad) as fullname,
t2.title as title,
t3.pass as password,
t3.phone_login as hat,
t2.time as date
FROM kullanici t1
INNER JOIN kullanici_tanim t2
ON t1.id = t2.usr_id
INNER JOIN dial_users t3
ON t1.agent_id = t3.user_id
GROUP BY t1.id
ORDER BY t1.id ASC
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