Union Vs Union All

Madhivanan — Thu, 03 Apr 2008 13:45:00 GMT

Well. Most of you know the diffrence between the two.

Here is one of the differences that is not known by newbies

When you use UNION, you cant include any column of type TEXT and NTEXT. But it is possible if you use UNION ALL

Declare @test table(i int, text_col text)

insert into @test

select 1,'some test string'union all

select 2,'some other test string'

--Error

select i,text_col from @test where i=1union

select i,text_col from @test where i=1

--No Error

select i,text_col from @test where i=1union all

select i,text_col from @test where i=1

Madhivanan : union vs union all