What happen with my codes???

Israel

Hi!

I wrote these codes to doesnt allow duplication records in my table. But I have a bugg and displaying error message on this line:

int numRecords = (int)comm.ExecuteScalar();

error message:

ExecuteScalar: Connection property has not been initialized.

My codes:

private void button1_Click(object sender, EventArgs e)

{

conn = new OleDbConnection(connstr);

comm = new OleDbCommand();

conn.Open();

connstr = "SELECT COUNT(*) FROM Not_duplicated_datas WHERE [username] = @username";

comm.CommandText = connstr;

comm.Parameters.Clear();

comm.Parameters.AddWithValue("@username", textBox1.Text);

int numRecords = (int)comm.ExecuteScalar();// the bugg it's here

if (numRecords == 0)

{

connstr = "INSERT INTO Not_duplicated_datas([username],[fillingcode],[branch],[department],[agency])VALUES(@username,@fillingcode,@branch,@department,@agency)";

comm.CommandText = connstr;

comm.Parameters.Clear();

comm.Parameters.AddWithValue("@username", textBox1.Text);

comm.Parameters.AddWithValue("@fillingcode", textBox2.Text);

comm.Parameters.AddWithValue("@branch", textBox3.Text);

comm.Parameters.AddWithValue("@department", textBox4.Text);

comm.Parameters.AddWithValue("@agency", textBox5.Text);

comm.ExecuteNonQuery();

MessageBox.Show("Created Successfully ..");

}

else

{

MessageBox.Show("A record with a user name of {0} already exists", textBox1.Text);

}

conn.Close();

3 Replies

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Israel11y ago
see what I do as you ask me to do:

private void button1_Click(object sender, EventArgs e)
{
conn = new OleDbConnection(connstr);
comm = new OleDbCommand();
comm.Connection = conn;// new line added
conn.Open();
connstr = "SELECT COUNT(*) FROM Not_duplicated_datas WHERE [username] = @username";
comm.CommandText = connstr;
comm.Parameters.Clear();
comm.Parameters.AddWithValue("@username", textBox1.Text);
int numRecords = (int)comm.ExecuteScalar();
if (numRecords == 0)
{
connstr = "INSERT INTO Not_duplicated_datas([username],[fillingcode],[branch],[department],[agency])VALUES(@username,@fillingcode,@branch,@department,@agency)";
comm.CommandText = connstr;
comm.Parameters.Clear();
comm.Parameters.AddWithValue("@username", textBox1.Text);
comm.Parameters.AddWithValue("@fillingcode", textBox2.Text);
comm.Parameters.AddWithValue("@branch", textBox3.Text);
comm.Parameters.AddWithValue("@department", textBox4.Text);
comm.Parameters.AddWithValue("@agency", textBox5.Text);
comm.ExecuteNonQuery();
MessageBox.Show("Created Successfully ..");
}
else
{
MessageBox.Show("A record with a user name of {0} already exists", textBox1.Text);
}
conn.Close();

Its works but there is one point important in this logic.
When I insert the same name already existing in my table its inform that its already in the table. But when I insert another one name or want to save a new record in my table and click on the same button. There is this message: An OLE DB Provider was not specified in the ConnectionString. An example would be, 'Provider=SQLOLEDB;'.
Curiosly, its happen only when I click twice on the button (It's not good)
Muhammad Aqib Shehzad11y ago
try this link.

http://stackoverflow.com/questions/5866046/executereader-connection-property-has-not-been-initialized

or

you have not used connection object with command try to use just like mentioned in link.
Yadlapalli Srikanth11y ago
//Add this line of code. Hope your issue will be resolved

comm.Connection = conn;