SQL union all的使用

背景：

公司业务开发需要将两个取出两个相同表结构（原料、辅料）的数据，组成一个新视图，使用了UNION ALL

SET QUOTED_IDENTIFIER ON
SET ANSI_NULLS ON
GOCREATE view vw_rawmaterial_ny_list
as
(
select id,ccode,ccommtype,ccompany,ctypecode,cconneed,ccontype,ccorpcode,cdelay,cdepcode,cdepname,cmaker,cmakercode,cpaytype,cposcode,cprice,cstate,ctesttype,cweitype,ddate,cvencode,cvenname,cpurtype,ctimestamp from op_rawmaterial_ey
union all
select id,ccode,ccommtype,ccompany,ctypecode,cconneed,ccontype,ccorpcode,cdelay,cdepcode,cdepname,cmaker,cmakercode,cpaytype,cposcode,cprice,cstate,ctesttype,cweitype,ddate,cvencode,cvenname,cpurtype,ctimestamp from op_rawmaterial_ef
)
GO

介绍：

union all将两个结果集合并后就返回结果。因此，如果返回的两个结果集中有重复的数据，那么返回的结果就会包含重复的数据。