SQL Server- update values from one column in same

问题:

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

I wrote a fiddle to try it out, but for some reason it isn't updating.

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

Any reason why my values in TYPE1 are not updating?

回答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

回答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

回答3:

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.

回答4:

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

回答5:

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;

回答6:

Your select statement was before the update statement see Updated fiddle