Adding and populating a column to existing table

Sorry I'm pretty new to SQL so I don't know if this is a simple question. I have a table, and I am trying to add a column to the table and populate this column using what would be called an 'IF' function in Excel.

Basically 'column A' has numbers in it. I want SQL to look at 'column A' and if the first 5 digits of the number in 'column A' are 00001, then put 'description A' into new column 'column B'. If the first 5 digits of the number in 'column A' are 00002, then put 'description B' into 'column A' etc.

Any ideas?...If the first 5 digits of the number in 'column A' are 00002, then put 'description B' into 'column A' etc.

Are you sure, or you just made mistake and both descriptions should be in Column B? I assume so, otherwise you would rewrite your numbers in colA

create table t(colA varchar(30))
go

insert into t values('000012')
insert into t values('000023')
insert into t values('123445')
go

alter table t add colB varchar(30)
go

update t
set colB = case when colA like '00001%' then
'description A'
when colA like '00002%' then
'description B'
end
go

note: when you create your table and colA is integer you won't be able found out how many zeros are in the begining as zeros at the begining are ignored|||Thanks very much that's really helpful! :cool: