什么导致“子查询返回超过 1 行”错误？

Question

I'm trying to add a new Back Order to the Back Order table in my MYSQL database. The problem I'm getting is that when I try to select the Supplier_ID to add it to the Back Order Table, the program gives me an error that says "Subquery returns more than 1 value".

Supplier Table (Unsure how to properly structure it)

| Supplier_ID | SupName |

| 1| EWS |

| 6 | Franklin Bakery |

Back Order Table

| BackOr_ID | Supplier_ID | BackOr_Org_Date | Sup_Name |

The MYSQL query I'm currently using is:

 CREATE DEFINER=`root`@`%` PROCEDURE `sp_BackOrder`( in supname varchar(50), in dat date ) BEGIN insert into Back_Order ( Supplier_ID, BackOr_Org_Date, Sup_Name ) values ( (select Supplier_ID from Supplier Where SupName = supname), dat, supname ); END

The C# Code that uses the query is:

 MySqlCommand cmd = new MySqlCommand("sp_BackOrder", new MySqlConnection(*Connection String*)); cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.Add(new MySqlParameter("supname", Supp_Name)); //Supp_Name is the Supplier Name (a string variable) cmd.Parameters.Add(new MySqlParameter("dat", DateTime.Now.ToShortDateString())); //dat is the date the Order is placed cmd.Connection.Open(); cmd.ExecuteNonQuery(); cmd.Connection.Close();

The only error I get is that the Subquery (Which I assume is the Select Query) returns more than 1 value. I've tried looking around and even looked on Stackoverflow but couldn't find any solution to the problem. Any help would be appreciated.

Answer 1

It would need to look like:

delimiter $$
CREATE DEFINER=`root`@`%` PROCEDURE `sp_BackOrder`
(   in p_supname varchar(50),
    in p_dat date
)
BEGIN
    insert into Back_Order(Supplier_ID, BackOr_Org_Date, Sup_Name)
    select Supplier_ID, p_dat, p_supname from Supplier Where SupName = p_supname;
END$$
delimiter ;

or

CREATE DEFINER=`root`@`%` PROCEDURE `sp_BackOrder`
(   in p_supname varchar(50),
    in p_dat date
)
BEGIN
    insert into Back_Order(Supplier_ID, BackOr_Org_Date, Sup_Name)
    select Supplier_ID, p_dat, p_supname from Supplier Where SupName = p_supname;
END

Same deal in both just depending on your DELIMITER needs.

Answer 2

The parameter name supname of procedure and column name SupName are same. Change parameter name to something other than column name.

CREATE DEFINER=`root`@`%` PROCEDURE `sp_BackOrder`(
in selectedSupname varchar(50),
in dat date
)
BEGIN
insert into Back_Order
(
Supplier_ID,
BackOr_Org_Date,
Sup_Name
)
values
(
(select Supplier_ID from Supplier Where SupName = selectedSupname),
dat,
selectedSupname
);

END