R Restart1 Unregistered / Unconfirmed GUEST, unregistred user! 2002-10-23 #1 A,B,C3个表，选出This字段，但是要distinct的，一句SQL怎么说？ 我用ADOQuery。
D dhl2001 Unregistered / Unconfirmed GUEST, unregistred user! 2002-10-23 #2 select distinct xx from (select xx from a union select xx from b union select xx from c )
U ugvanxk Unregistered / Unconfirmed GUEST, unregistred user! 2002-10-23 #3 好像union 就是distinct的，union all 是全部的
