为什么我从此存储过程中收到Null? [英] Why do I receive Null from this stored procedure?

问题描述

我用输出参数@name创建了一个存储过程.但是当我调用它时，我收到 Null.如何正确调用该过程或该过程有错误?

I created a stored procedure with the output parameter @name. But when I call it, I receive Null. How do I correctly call the procedure or is there an error in the procedure?

CREATE PROCEDURE GetName(IN kartennummer CHAR(16), OUT name VARCHAR(91))
BEGIN
SELECT @name = (SELECT CONCAT_WS(' ', Vorname, Nachname) FROM Kunden kund JOIN Konten kont WHERE kund.KundenID = kont.KundenID AND kont.Kartennummer = kartennummer);
END;

我这样调用程序:

CALL GetNAME("7717015800401117", @name);

为什么我会收到Null而不是名称?Select 语句单独起作用.

Why do I receive Null and not the name? The Select statement alone works.

推荐答案

DELIMITER $$
CREATE PROCEDURE GetName(IN kartennummer CHAR(16), OUT name VARCHAR(91))
BEGIN
    SELECT 
        CONCAT_WS(' ', Vorname, Nachname)
        INTO 
        name
    FROM
        Kunden kund
            JOIN
        Konten kont
    WHERE
        kund.KundenID = kont.KundenID
            AND kont.Kartennummer = kartennummer;
END;
DELIMITER ;

这将只能工作，如果结果如果选择查询IHAS ONL1名称，但假设是您

This will only work , if the result if the select query ihas onl1 name, but assume that is the case for you

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