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

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?

update TABLE_1 a set COLUMN_1 = (select COLUMN_2 from TABLE_1 b where a.ID = b.ID)

UPDATE `tbl_user` SET `name`=concat('tbl_user.first_name','tbl_user.last_name') WHERE student_roll>965

UPDATE TABLE_NAME SET COLUMN_A = COLUMN_B;

Much easier. At least on Oracle SQL, i don't know if this works on other dialects as well.

You put select query before update queries, so you just see initial data. Put select * from stuff; to the end of list.

This answer about updating column from a part of another column in the same table.

update T1
set domainname = (New value) --Example: (SELECT LEFT(TableName.col, CHARINDEX('@',TableName.col)-1) STRIPPED_STRING FROM TableName where TableName.col = T2.Emp_ID)
from TableName T1
INNER JOIN
    TableName T2
ON 
    T1.ID= T2.ID;

Your select statement was before the update statement see Updated fiddle

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