book_return.sql

图书馆系统建立

CREATE PROCEDURE Book_Return
(@book_id int)
 AS
IF @book_id IS NULL
BEGIN
   PRINT'必须提供要还的图书ID！'
   RETURN  10
IF NOT EXISTS(SELECT * FROM book_info WHERE book_id=@book_id)
BEGIN
  PRINT'这本书不是本馆的书！'
  RETURN -20 
END
UPDATE book_info SET book_state_id=2 WHERE book_id=@book_id
RETURN 0