I am getting an error while inserting records into sqldata table using C# windows form. Here is my code. I am unable to locate the error

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i tried to figure out. but failed.if i changed sqldatareader into comments mode it will work.please help me on this.
Giving error like

Must declare the scalar variable "@label2".

What I have tried:

con = new SqlConnection(@"Data Source=M2\SQL2016;Initial Catalog=inventoryDB;Integrated Security=True");// Database connetion path
                con.Open();
                cmd = new SqlCommand("INSERT INTO companyDB(compname) VALUES (@label2)", con);// inserting into database
                SqlDataReader dr = cmd.ExecuteReader();
                dr.Close();

                cmd.Parameters.Add("@label2", cmpname.Text);
                MultipleActiveResultSets = true;
               //duplicatecheck();
                cmd.ExecuteNonQuery();
                MessageBox.Show("Saved Successfully");
                cmpname.Text = "";
                cmpname.Focus();
                con.Close();

Posted 3-Mar-17 23:25pm

Member 13037527

Updated 3-Mar-17 23:48pm

v3

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Richard MacCutchan · Answer 1 · 2017-03-03T23:48:00

Solution 1

Of course it will work. Look at the code, you are calling ExecuteReader on a INSERT statement. Also you have not declared the parameter value.

And please, never do the following

C#

MessageBox.Show("Saved Successfully");

when you have not checked that the command succeeded. You could run for weeks, months or even years without knowing that your database is garbage. System commands return status information for a good reason, make use of it.

Posted 3-Mar-17 23:48pm

Richard MacCutchan

Updated 3-Mar-17 23:51pm

v2

Comments

Member 13037527 4-Mar-17 6:18am

@Richard Sql datareader I used to check for duplicates.so that prevent to enter duplicates.

Richard MacCutchan 4-Mar-17 6:19am

You are not checking anything, and your SQL statement is still incorrect.

Member 13037527 4-Mar-17 6:24am

@richard for duplicate check i wrote this but error is coming "

There is already an open DataReader associated with this Command which must be closed first.

So iclosed there but still error is coming so i converted that two lines as comments

public bool duplicatecheck()
            {
            
            string constring = @"Data Source=M2\SQL2016;Initial Catalog=inventoryDB;Integrated Security=True"; 
            SqlConnection con = new SqlConnection(constring);// data connection
            SqlCommand cmd = new SqlCommand("Select count(*) from companyDB where compname= @alias", con);
            cmd.Parameters.AddWithValue("@alias", this.cmpname.Text);
            con.Open();
            
            
            SqlDataReader dr = cmd.ExecuteReader();
            
            
            

            int TotalRows = 0;
            TotalRows = Convert.ToInt32(cmd.ExecuteScalar());
            //dr.Close();
            if (TotalRows > 0)
            {
                MessageBox.Show("Alias " + dr[1].ToString() + " Already exist");
                
                return true;
                

            }
            else
            {
                return false;
            }

Richard MacCutchan 4-Mar-17 6:33am

You are calling ExecuteReader immediately followed by ExecuteScalar. You need to stop and look closely at the workflow of your code, rather than randomly adding or modifying commands.