SQL条件的

我有一个sql：

Select 
    t1.field01, 
    t1.field02, 
    t2.name02, 
    t2.surname02, 
from 
    lib01/FirstFile as t1, 
    lib02/SecondFile (lib02/ThirdFile) as t2 
where 
    t1.field01 = t2.field02 (or t3.filed02)

我需要有一个条件，如果t1.field02等于AX，我必须读取第二个文件lib02/SecondFile，如果t1.field02等于BX，我必须读取第三个文件lib02/ThirdFile

Select      
    CASE 
       WHEN ((Select t1.field02 from lib01/FirstFile as t1 ) = AX)
           THEN Select t2.name02, t2.surname02 
                from lib02/SecondFile (lib02/ThirdFile) as t2 
    CASE 
       WHEN ((Select t1.field02 from lib01/FirstFile as t1 ) = BX)
          THEN Select t3.name02, t3.surname02 
               from (lib02/ThirdFile) as t3
    END

如果检索不是您想要的，但这是逻辑，请更改每个THEN子句之后的代码

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并尽量避免使用join的旧语法

您使用的是哪种DBMS？您应该真正停止在where子句中使用那些古老的、过时的、脆弱的隐式连接，而是使用显式连接运算符