JOIN on like comparison

declare @tbl table (aaa varchar(50))

declare @src table (aaa varchar(50))

insert into @tbl values ('aaa'), ('aaabcd'), ('bcd'), ('zzzaaa')

insert into @src values ('aaa')

-- select only equel strings (same as t.aaa = s.aaa)

select * from @tbl t join @src s on t.aaa like s.aaa

update @src set aaa = '%' + aaa + '%'

-- select all the records from t that contain s.aaa

select * from @tbl t join @src s on t.aaa like s.aaa