Error:Index and length must refer to a location within the string.

[virtuoso]

Hi,
what is rong with my code?

int i = int.Parse(txtpret.Text);
                string query1 = "UPDATE Movie set pret = pret + '" + i + "'";
                string query2 = "UPDATE Movie set pret = pret - '" + i + "'";
 
                MySqlCommand cmd1 = new MySqlCommand(query1, connection);
                MySqlCommand cmd2 = new MySqlCommand(query2, connection);
 
 
                //Execute command
                if (rbmareste.Checked)
                    cmd1.ExecuteNonQuery();
                if (rbscade.Checked)
                    cmd2.ExecuteNonQuery();  //here apears the error; cmd1 works fine;
 

[nukefusion]

Judging by the fact that you convert the contents of txtPret to an Integer I'm guessing it's supposed to be a number, however, in your SQL statement your manipulating it as if it was a string. That's your error. Your code should read:

string query1 = "UPDATE Movie set pret = pret + " + i; 
string query2 = "UPDATE Movie set pret = pret - " + i; 
 

The first query passed because in effect it performs a concatenation. If pret=1 and i=1, after the update pret=11.

Hope this helps.

[virtuoso]

Thanks for the answer;
I manage to solve the problme. Now my ode looks like this:

# string query1 = "UPDATE Movie set pret = pret + '" + i + "'";
# string query2 = "UPDATE Movie set pret = pret - " + i + "";
 

form query2 i delete the ' ' but query1 looks just as before and works fine; I's strange but it's work;

[nukefusion]

@virtuoso
Glad you have it working.

I'd double check your data because the first command is still treating i as a string while your second one is now treating it as an integer.

If your data's okay it may be because your SQL implementation is implicitly casting it back to an integer for you. If that's the case, although it works, it's unnecessary overhead and inconsistent. You should still consider modifying the first statement to treat i as an integer; it is after all, a number.