Check if record exists in DB Mysql c#

hi experts my code is like that check on table1 if textbox1.Text exist if yes go to table2 and check if textbox1.text exist and if textbox2.Text exist if they exist open the form if not insert them and open the form and if textbox1.text exist and textbox2.text doesn't exist close form

i wrote this :

MySqlConnection con = new MySqlConnection(connectionString);
i = 0;
con.Open();
MySqlCommand cmd = con.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "select * from informat where u_ser = '" + metroTextBox2.Text + "' ";
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
da.Fill(dt);
i = dt.Rows.Count;
int userial = metroTextBox2.Text.Length;
if (userial >= 5 || metroTextBox2.Text == null)
{
MySqlConnection conet = new MySqlConnection(connectionString);
conet.Open();
MySqlCommand cmsd = conet.CreateCommand();
cmsd.CommandType = CommandType.Text;
cmsd.CommandText = "select * from alred where u_ser = '" + metroTextBox2.Text + "'and u_ip = '" + textBox1.Text + "'";
cmsd.ExecuteNonQuery();
DataTable ddts = new DataTable();
MySqlDataAdapter ddas = new MySqlDataAdapter(cmsd);
ddas.Fill(ddts);
if (textBox1.Text != null)
{
MessageBox.Show("Your Serial is used in another computer");
this.Close();
}
else if (metroTextBox2.Text == null & textBox1.Text == null)
{
ireview frms = new ireview();
this.Hide();
frms.Show();
}
else if (metroTextBox2.Text != null && textBox1.Text != null)
{
MySqlConnection conect = new MySqlConnection(connectionString);
conect.Open();
MySqlCommand cmsdd = conet.CreateCommand();
cmsdd.CommandType = CommandType.Text;
cmsdd.CommandText = "INSERT INTO alred (u_ser, u_ip) " + " Values ('" + metroTextBox2.Text + "', '" + textBox1.Text + "')";
cmsdd.ExecuteNonQuery();
DataTable sddts = new DataTable();
MySqlDataAdapter sddas = new MySqlDataAdapter(cmsdd);
sddas.Fill(sddts);
ireview frms = new ireview();
this.Hide();
frms.Show();
}
}
else
{
MessageBox.Show("You Serial Doesn't Exist");
}
}

but it doesn't work its always go directly to insert and it insert it two times

3 Replies

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Puneet Kankar9y ago
Accepted answer
you check Data from table1 like int i = select count(name) from table1 where name= textbox.text then u check i value if value is 0 then insert data.
+1
Puneet Kankar9y ago
hi friend please refer to this link https://stackoverflow.com/questions/32670906/check-if-a-record-exists-in-mysql-database https://stackoverflow.com/questions/1676551/best-way-to-test-if-a-row-exists-in-a-mysql-table
0
Ilyas Zahir9y ago
is there any example of that ?
0