How can I update various sql columns based on another column of the same row?

Question

I am running SQL Server and am needing to update hundreds of entries. Column A has unique values and based on that I need to update column B of the same table, all with different values. Essentially I am looking for a way to perform the following but in a bulk manner:

UPDATE table
set column B = 'value'
where column A = 'unique value'

Answer 1

Is this what you are expecting,

UPDATE table
set column B = case when column A = 5 then 'unique string' end;