mysql 存储过程判断重复的不插入数据

delimiter $$create procedure proc_add_book(in $bookName varchar(200),in $price float)begin  declare $existsFlag int default 0;  select bookId into $existsFlag from book where bookName = $bookName limit 1;  if bookId > 0 then  #if not exists (select * from book where bookNumber = $bookName) then    insert into book(bookNumber,price) values($bookName,$price);  end if;end$$delimiter ;