Question

我想在phpmyadmin中做一些功能

DELIMITER //
CREATE FUNCTION total_bayar (order_id char(10)) 
RETURNS double
DETERMINISTIC
BEGIN 
  DECLARE dist double;
  SET dist = SELECT sum(qty * price) FROM detail_masakan WHERE order_id = order_id;
  RETURN dist;
END//
DELIMITER ;

查询SQL：Dokumentasi

CREATE FUNCTION total_bayar (order_id char(10)) 
RETURNS double
DETERMINISTIC
BEGIN 
  DECLARE dist double;
  SET dist = SELECT sum(qty * price) FROM detail_masakan WHERE order_id = order_id;
  RETURN dist;

END

MySQL说：Dokumentasi

＃1064-您的SQL语法有错误；检查与您的MariaDB服务器版本相对应的手册以获取正确的语法，以在'SELECT sum（qty * price）FROM FROM detail_masakan WHERE order_id = order_id;
附近使用在第6行返回”

Answer 1

似乎不喜欢您使用SET命令。改用SELECT ... INTO。

DELIMITER // 
CREATE FUNCTION total_bayar (order_id char(10)) RETURNS double 
DETERMINISTIC 
BEGIN 
    DECLARE dist double; 

    SELECT sum(qty * price) INTO dist FROM detail_masakan WHERE order_id = order_id; 
    RETURN dist; 
END// DELIMITER ;

Answer 2

您需要在子查询中加上括号：

SET dist = (SELECT sum(qty * price) FROM detail_masakan WHERE order_id = order_id);

但是，这仍然不能满足您的要求，因为变量名被弄乱了-并将与列名混淆。

我建议：

DELIMITER //

CREATE FUNCTION total_bayar (in_order_id char(10)) 
RETURNS double
DETERMINISTIC
BEGIN 
  DECLARE out_dist double;

  SELECT out_dist := sum(dm.qty * dm.price)
  FROM detail_masakan dm
  WHERE dm.order_id = in_order_id;

  RETURN out_dist;
END//
DELIMITER ;

创建函数返回双精度值

2 个答案: