UPDATE and REPLACE part of a string

query:

UPDATE tablename 
SET field_name = REPLACE(field_name , 'oldstring', 'newstring') 
WHERE field_name LIKE ('oldstring%');

To make the query run faster in big tables where not every line needs to be updated, you can also choose to only update rows that will be modified:

UPDATE dbo.xxx
SET Value = REPLACE(Value, '123', '')
WHERE ID <= 4
AND Value LIKE '%123%'

You don't need wildcards in the REPLACE - it just finds the string you enter for the second argument, so the following should work:

UPDATE dbo.xxx
SET Value = REPLACE(Value, '123', '')
WHERE ID <=4

If the column to replace is type text or ntext you need to cast it to nvarchar

UPDATE dbo.xxx
SET Value = REPLACE(CAST(Value as nVarchar(4000)), '123', '')
WHERE ID <=4

Try to remove % chars as below

UPDATE dbo.xxx
SET Value = REPLACE(Value, '123', '')
WHERE ID <=4