Question

我有一个存储过程，应检查正在添加的艺术家是否在Allowed Nationality表中，但它不起作用。代码插入艺术家是否在Allowed Nationality表中。谁能告诉我我做错了什么？

DELIMITER //
CREATE PROCEDURE `InsertNewArtistCheck`
   (IN newLastName Char(25),
    IN newFirstName Char(25),
    IN newNationality Char(30),
    IN newDateOfBirth Numeric(4),
    IN newDateDeceased Numeric(4))
BEGIN
DECLARE varRowCount Int;
   SELECT Nation INTO varRowCount
   FROM ALLOWED_NATIONALITY
   WHERE Nation = newNationality;

   IF (varRowCount < 0)
   THEN
       ROLLBACK;
          SELECT 'Nationality Not Allowed' AS ErrorMessage;
   END IF;
   INSERT INTO ARTIST (LastName, FirstName, Nationality, 
                       DateOfBirth, DateDeceased)
               VALUES (newLastName, newFirstName, newNationality, 
                      newDateOfBirth, newDateDeceased);
   SELECT 'New artist data added to database' AS InsertStatus;
END//
DELIMITER ;

Answer 1

尝试以下更改：

 DECLARE varRowCount Int;

       SELECT count(*) INTO varRowCount
       FROM ALLOWED_NATIONALITY
       WHERE Nation = newNationality;

       IF (varRowCount < 1)
       THEN
           ROLLBACK;
           SELECT 'Nationality '+newnationality+' not Allowed' AS ErrorMessage;
           RETURN
       END IF;

您正在尝试将字符值（NATION）放入数字变量（varRowCount）。你真正想要的是确定与新艺术家国家相匹配的国家数量（希望是1）。您也不需要ROLLBACK语句，因为存储过程没有完成“撤消”所需的任何操作

Answer 2

将被关闭，仍然......

见这一行：

IF（varRowCount＆lt; 0）

告诉我你认为SQL Server会在什么条件下返回负数行？

应该等于0，不小于。

SQL中的存储过程

2 个答案: