创建 MySQL 过程

Question

我目前正在尝试在存储在 Google Cloud Platform 上的 MySQL 上创建存储过程。

看到我可以在本地创建过程，SQL 是正确的，但我不知道为什么它不能从命令行运行：

mysql> CREATE PROCEDURE helpme
    -> (
    ->  @cid varchar(4)
    -> )
    -> AS
    -> DECLARE @res_cnt INT
    -> DECLARE @name CHAR(10)
    ->
    -> SELECT @res_cnt = COUNT(*) FROM dbo.TripGuides WHERE GuideNum = @cid
    -> SELECT @name = LastName FROM dbo.Guide WHERE GuideNum = @cid
    -> PRINT @name + ' has ' +  CAST (@res_cnt AS VARCHAR(10))+' guides.';
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '@cid varchar(4)
)
AS
DECLARE @res_cnt INT
DECLARE @name CHAR(10)

SELECT @res_cn' at line 3
mysql>

我尝试了一些不同的方法，谢谢我遇到了。在声明 @cid 时，我都尝试了

@cid CHAR(4)
@cid VARCHAR(4)

导致抛出相同的错误。

Answer 1

供 MySQL 使用

CREATE PROCEDURE helpme ( cid VARCHAR(4) )
SELECT CONCAT( ( SELECT LastName 
                 FROM Guide 
                 WHERE GuideNum = cid ), 
               ' has ', 
               ( SELECT COUNT(*) 
                 FROM TripGuides 
                 WHERE GuideNum = cid ), 
               ' guides.'
             ) AS message;

出于好奇，我将如何将 res_cnt 和 name 声明为我之前所做的原始 SQL 调用？

CREATE PROCEDURE helpme ( cid VARCHAR(4) )
BEGIN
    DECLARE res_cnt INT;
    DECLARE `name` CHAR(10);

    SELECT COUNT(*) INTO res_cnt FROM TripGuides WHERE GuideNum = cid;
    SELECT LastName INTO `name` FROM Guide WHERE GuideNum = cid;
    SELECT CONCAT( `name`, ' has ', res_cnt, ' guides.' ) AS output_message;
END

并且不要忘记在这种情况下重新分配 DELIMITER。