SQL关键字 union、intersect、except用法

1.union是A集合和B集合的并集；

select 'S_E_Product' FormType,Name,Code,Version,ProjectInfoID,WBSID,MajorValue from  S_E_Product where ID='ac130126-8cf2-48e5-8584-f1c737dd3678'
union
select 'S_E_ProductVersion' FormType,Name,Code,Version,ProjectInfoID,WBSID,MajorValue from  S_E_ProductVersion where 
ProductID='ac130126-8cf2-48e5-8584-f1c737dd3678'

2.intersect是A集合和B集合的交集；

select Name,Code,Version,ProjectInfoID,WBSID,MajorValue from  S_E_Product where ID='ac130126-8cf2-48e5-8584-f1c737dd3678'

intersect

select Name,Code,Version,ProjectInfoID,WBSID,MajorValue from  S_E_ProductVersion where 
ProductID='ac130126-8cf2-48e5-8584-f1c737dd3678'

3.except是A集合减去B集合的结果；

select Name,Code,Version,ProjectInfoID,WBSID,MajorValue from  S_E_ProductVersion where 
ProductID='ac130126-8cf2-48e5-8584-f1c737dd3678'
except
select Name,Code,Version,ProjectInfoID,WBSID,MajorValue from  S_E_Product where ID='ac130126-8cf2-48e5-8584-f1c737dd3678'

注：都是返回的是非重复值，联合查询的表字段必须一致。