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:<

Answer 1

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;

Answer 2

Your select statement was before the update statement see Updated fiddle