# MySQL 标签
热身 在开始之前，请先看下以下四条SQL，请问它们的数据逻辑是一样的吗，或者说它们的结果必然一样的吗？（这里不考虑SQL的效率，优化） -- SQL1 select a.k1, a.v1, b.k2, b.v2 from A a left join B b on a.k1=b.k2 and b.status = 0 where a.status = 0 -- SQL2 select a.k1, a.v1, b.k2, b.v2 from A a left join B b on a.k1 = b.k2 where a.status = 0 and b.status = 0 -- SQL3 select a.k1, a.v1, b.k2, b.v2 from A a left join ( select k2, v2 from B where status = 0 ) b on a.k1 = b.k2 where a.status = 0 -- SQL4 select a.k1, a.v1, b.k2, b.v2 from ( select k1, v1 from A where sta....

JoinOnConstant(常数)的逻辑拾遗