使用sql查询在oracle 11g中连接多个表

Question

我想要treat_info表的所有列以及相应的处理表和设备表费用。什么是sql查询？ 3表图像链接如下

Answer 1

我决定使用“LEFT JOIN”来确定这些字段是否为TREATMENT，而EQUIPMENT是外键。

因此，您有FEE值（如果存在）。

select
T1.*
,T2.FEE as TREATMENT_FEE
,T3.FEE as EQUIP_FEE
from TREAT_INFO as T1
left join TREATMENT as T2 on T2.TREATMENT = T1.TREATMENT
left join EQUIPMENT as T3 on T3.EQUIPMENT = T1.EQUIPMENT