Update values from one column in same table to another in SQL Server

Question

I'm trying to overwrite values that are found in TYPE1 with values that are found in TYPE2.

I wrote this SQL to try it out, but for some reason it isn't updating:

select * from stuff  update stuff set TYPE1 = TYPE2 where TYPE1 is null;  update stuff set TYPE1 = TYPE2 where TYPE1 ='Blank'; 

http://www.sqlfiddle.com/#!3/a4733/17

Any reason why my values in TYPE1 are not updating?

Answer 1

This works for me

select * from stuff  update stuff set TYPE1 = TYPE2 where TYPE1 is null;  update stuff set TYPE1 = TYPE2 where TYPE1 ='Blank';  select * from stuff 

Answer 2

UPDATE a SET a.column1 = b.column2 FROM myTable a  INNER JOIN myTable b on a.myID = b.myID 

in order for both "a" and "b" to work, both aliases must be defined