sql server update colA based on value in colB

I have to update a column in a table based on the value of another column in the same table.  

col A holds the varchar value of a number
col B is the range of that number

if col A = '30' then col B needs to be updated to '30-40'
if col A = '50' then col B needs to be updated to '50-100'

please help.
dhenderson12Asked:
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SharathData EngineerCommented:
How do you determine the ranges? Do you want a range of gap 10 or 50? What are all possible ranges you are looking for?
0
Scott PletcherSenior DBACommented:
You'd be far better off with colB as a computed column, since you wouldn't have to UPDATE when colA changed:

ALTER TABLE dbo.tablename
ADD ColB AS CASE
    WHEN colA LIKE '3[0-9]' OR colA = '40' THEN '30-40'
    WHEN colA LIKE '[56789][0-9]' OR colA = '100' THEN '50-100'
    END
0

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Microsoft SQL Server 2008

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