Subqueries in conditional statements

You can use subqueries in conditional statements. The preceding subquery that removed all records of sales of business books can be rewritten, as shown in the next example, to check for the records before deleting them:

if exists (select title_id 
    from titles 
    where type = "business")
begin
    delete salesdetail 
    where title_id in 
      (select title_id 
       from titles 
       where type = "business") 
end