SELECT a.id,a.selectFlag,a.content FROM T_A a,T_B b WHERE a.id=b.id_A and b.price>100
union
SELECT a.id,a.selectFlag,a.content FROM T_A a WHERE NOT EXISTS (SELECT id FROM T_B b where a.id=b.id_A) AND a.selectFlag=true;
union
SELECT a.id,a.selectFlag,a.content FROM T_A a WHERE NOT EXISTS (SELECT id FROM T_B b where a.id=b.id_A) AND a.selectFlag=true;
union all 可以把全部的结果列出来
具体看你的选择
union 可以把结果组合起来,但有相同记录就不能全部取完相同记录
下午结帖!