lan_13217的专栏

[code="sql"] select case when t1.pid is null then t2.pid else t1.pid end from t1 full join t2 on t1.pid = t2.pid [/code] http://www.builder.com.cn/2007/1008/540581.shtml

[code="java"] insert into "SR"(sid, rid,is_parse) select * from ( SELECT s.id as sid, r.id as rid,0 FROM "Segment" s ,"Rule" r where s.domain=r.domain order by sid,rid ) srall where not exist...

[code="java"] 索引类型 唯一索引：唯一索引不允许两行具有相同的索引值 主键索引：为表定义一个主键将自动创建主键索引，主键索引是唯一索引的特殊类型。主键索引要求主键中的每个值是唯一的，并且不能为空 聚集索引(Clustered)：表中各行的物理顺序与键值的逻辑（索引）顺序相同，每个表只能有一个 非聚集索引(Non-clustered)：非聚集索引指定表的逻辑顺序。数据存储...

sql分组查询最大记录 1. [code="sql"] select distinct first_value(emp_id) over(partition by emp_code order by tm.last_modify_tm desc) from employee tm [/code] 2. [code="sql"] select * from (selec...