CODEWITHSUNDEEP
c#
kielou
kielou

Reputation: 437

Trying to execute a query multiple times using while loop

I'm trying to execute a query for MySql using while loop but it gives me error and I don't have any idea how to fix it. Without the loop, the code works well.

Additional information: Object reference not set to an instance of an object.

Here is what i got:

String copies = txtcopies.Text;
int x = Convert.ToInt32(copies);
int n = 0;

while (n < x)
{
    string loadstring = @"server=localhost;database=librarys;userid=root;password=1234;";

    MySqlConnection conDataBase = new MySqlConnection(loadstring);

    MySqlCommand cmdDataBase = new MySqlCommand("SELECT func_add_book('" + this.lblbnum.Text + "','" + this.txtisbn.Text + "','" + this.txttitle.Text + "','" + this.txtauthor.Text + "','" + this.txtpublisher.Text + "','" + this.txtdate.Text + "','" + this.txtcost.Text + "');", conDataBase);
    string returnedValue = cmdDataBase.ExecuteScalar().ToString();

    n++;

    conDataBase.Open();
    ClearAllText(txtcopies);
    MessageBox.Show(returnedValue);
}

Upvotes: 0

Views: 1402

Answers (1)

Arun Kumar
Arun Kumar

Reputation: 957

The problem is that you are opening your connection after executing the query. Also you only need to open SQL connection once in your code. Try the below code and see if it works.

String copies = txtcopies.Text;
int x = Convert.ToInt32(copies);
int n = 0;
string loadstring = @"server=localhost;database=librarys;userid=root;password=1234;";
MySqlConnection conDataBase = new MySqlConnection(loadstring);
try
{
    conDataBase.Open();
    while (n < x)
    {
        MySqlCommand cmdDataBase = new MySqlCommand("SELECT func_add_book('" + this.lblbnum.Text + "','" + this.txtisbn.Text + "','" + this.txttitle.Text + "','" + this.txtauthor.Text + "','" + this.txtpublisher.Text + "','" + this.txtdate.Text + "','" + this.txtcost.Text + "');", conDataBase);
        string returnedValue = cmdDataBase.ExecuteScalar().ToString();
        n++;
        ClearAllText(txtcopies);
        MessageBox.Show(returnedValue);
    }
}
Catch (Exception Ex)
{
}
Finally
{
    conDataBase.Close()
}

Upvotes: 2

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