摘要：select m.id, m.a, n.id, n.a from (select t0.* from t t0where not exists (select 1 from t t1 where t1.sj = t0.sj and t1.a > t0.a)) mselect t0.* from t t0 where not exists (select 1 from t t1 where t1.sj = t0.sj and t1.a < t0.a)) nwhere m.sj = n.sj; 阅读全文

摘要：来自 http://www.cnblogs.com/sekihin/archive/2009/08/14/1545867.html【Postgresql】字符串操作函数函数：string || string　说明：String concatenation 字符串连接操作例子：'Post' || 'greSQL'　＝　PostgreSQL函数：string || non-string or non-string || string说明：String concatenation with one non-string input 字符串与非字符串类型进行连接操作例子 阅读全文