How to update multicolumn in SQL?

I need to write a SQL update query. I want to update where workorder=12300000 column1.TrimStart(B7CL).Addto(column2). But how can I do that in SQL Server 2005?

Convert this table:

workorder |column1            | column2         
12300000  |B7CL-B32-41-00-5A  | NULL
12400000  |B7CL-B33-42-00-5A  | NU开发者_如何学编程LL
12300000  |B7CL-B34-44-03-5A  | NULL
12600000  |B7CL-B35-45-01-5A  | NULL
12300000  |B7CL-B36-45-01-5A  | B36-45-01-5A

To this table:

workorder |column1            | column2
12300000  |B7CL-B32-41-00-5A  | B32-41-00-5A
12400000  |B7CL-B33-42-00-5A  | B33-42-00-5A
12300000  |B7CL-B34-44-03-5A  | B34-44-03-5A
12600000  |B7CL-B35-45-01-5A  | B35-45-01-5A
12300000  |B7CL-B36-45-01-5A  | B36-45-01-5A

Try something like:

UPDATE dbo.YourTable
SET column2 = SUBSTRING(column1, 6, 12)
WHERE column2 IS NULL

or if you want to apply your WHERE clause (that you mention):

UPDATE dbo.YourTable
SET column2 = SUBSTRING(column1, 6, 12)
WHERE workorder = 12300000

However, your sample doesn't seem to use this WHERE clause.....

 Update Table
    Set Column2 = Replace(Column1, 'B7CL-','')
    Where Column2 Is Null
    AND workorder=12300000

How about something like

UPDATE Table
SET Column2 = REPLACE(Column1,'B7CL-','')
WHERE Column2 ISNULL

or with the where clause

UPDATE Table 
SET Column2 = REPLACE(Column1,'B7CL-','') 
WHERE Column2 ISNULL
AND workorder=12300000