执行存储过程时 ExecuteNonQuery() 返回 -1 [英] ExecuteNonQuery() returns -1 when execute the stored procedure

问题描述

我正在尝试在 Visual Studio 中执行存储过程.下面给出.

I'm trying to execute stored procedure in Visual Studio. Its given below.

CREATE PROCEDURE [dbo].[addStudent] 
    @stuName varchar(50), 
    @address varchar(100),
    @tel varchar(15),
    @etel varchar(15),
    @nic varchar (10),
    @dob date


AS 
BEGIN   
    SET NOCOUNT ON;

    DECLARE @currentID INT
    DECLARE @existPerson INT
    SET @existPerson = (SELECT p_ID FROM Student WHERE s_NIC = @nic);
    IF @existPerson = null
        BEGIN
            INSERT INTO Person (p_Name, p_RegDate, p_Address, p_Tel, p_EmergeNo, p_Valid, p_Userlevel)
            VALUES (@stuName,  GETDATE(), @address, @tel, @etel, 0, 'Student' );
            SET @currentID = (SELECT MAX( p_ID) FROM Person); 
            INSERT INTO Student (p_ID, s_Barcode, s_DOB, s_NIC) VALUES (@currentID , NULL, @dob, @nic);
            return 0;
        END
    ELSE
        return -1;
END 

我使用下面的代码来这样做.

Im doing so by using this code below.

        SqlConnection con = new SqlConnection();
        Connect conn = new Connect();
        con = conn.getConnected();
        con.Open();
        cmd = new SqlCommand("addStudent", con);
        cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.Add("@stuName", SqlDbType.VarChar).Value = nameTxt.Text.ToString();
                cmd.Parameters.Add("@address", SqlDbType.VarChar).Value = addressTxt.Text.ToString();
                cmd.Parameters.Add("@tel", SqlDbType.VarChar).Value = telTxt.Text.ToString();
                cmd.Parameters.Add("@etel", SqlDbType.VarChar).Value = emerTxt.Text.ToString();
                cmd.Parameters.Add("@nic", SqlDbType.VarChar).Value = nicTxt.Text.ToString();
                cmd.Parameters.Add("@dob", SqlDbType.DateTime).Value = dobTime.Value.ToString("MM-dd-yyyy");

                    int n = cmd.ExecuteNonQuery();
                    MessageBox.Show(n.ToString());

但它返回-1.我通过输入从调试中捕获的相同值来尝试这个存储过程.它成功了.可能的错误是什么?非常感谢！

But it returns me -1. I tried this stored procedure by entering the same values I captured from debugging. It was successful. What can be the possible error? Thanks a lot!

推荐答案

不要使用= null，使用is null

IF @existPerson is null

当你比较任何东西 = null 时，结果总是假的(除非你有 set ansi_nulls off，你不应该这样做，因为这样的选项已被弃用)

When you compare anything = null the result is always false (unless you have set ansi_nulls off, which you shouldn't, as such an option is deprecated)

更好的是，您可以使用

IF NOT EXISTS (SELECT p_ID FROM Student WHERE s_NIC = @nic)

另外，你应该使用 SCOPE_IDENTITY() 而不是 SET @currentID = (SELECT MAX( p_ID) FROM Person);

Also, you should use SCOPE_IDENTITY() instead of SET @currentID = (SELECT MAX( p_ID) FROM Person);

SET @currentID = SCOPE_IDENTITY()

最后还需要添加一个参数来收集返回值

Finally you also need to add a parameter to collect the return value

   SqlParameter retValue = cmd.Parameters.Add("return", SqlDbType.Int);
   retValue.Direction = ParameterDirection.ReturnValue;

然后

MessageBox.Show(retValue.Value);

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