How we Delete data in data Gridview and Database table

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Hellow Every one i have a problem during Developed our final symester Database Project
the code you see below is delete data in datagirdview but not delete data in database table ? And my database table varible type is nvarchar and when we delete data in datagridview they display the follow error
system.data.sqlclient.sqlException(0*8103365) Conversion failed when converting the
'nvarchar' value "مال مسروقہ و برامدگی" to datatype int at system.data........

C#

private void firdel_Click(object sender, EventArgs e)
      {
          DataTable tb = new DataTable();
          connection_crime cr = new connection_crime();
          SqlConnection abc = new SqlConnection(cr.crim());
         // abc.Open();
          for (int i = 0; i < firGridView1.Rows.Count; i++)
          {
              DataGridViewRow dr = firGridView1.Rows[i];
              if (dr.Selected == true)
              {
                  firGridView1.Rows.RemoveAt(i);
                  try
                  {

          foreach (DataGridViewRow row in firGridView1.SelectedRows)
              if (!row.IsNewRow) firGridView1.Rows.Remove(row);
          int selectedCount = firGridView1.SelectedRows.Count;
          while (selectedCount > 0)
          {
              if (!firGridView1.SelectedRows[0].IsNewRow)
                  firGridView1.Rows.RemoveAt(firGridView1.SelectedRows[0].Index);
              selectedCount--;
          }


                      abc.Open();
                      SqlCommand cmd = new SqlCommand("Delete from FIRrecord where namplc2 =" + i + "", abc);
                      cmd.ExecuteNonQuery();
                      SqlDataReader c = cmd.ExecuteReader();
                      abc.Close();
                  }
                  catch (Exception ex)
                  {
                      MessageBox.Show(ex.ToString());
                  }
              }

plz any one tell me how we correct the above code

Posted 12-Apr-12 21:12pm

Khan Rashid

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Comments

swapnilKumbhar 13-Apr-12 5:37am

This method is very complicated.Use SQL Notification.

ZurdoDev 13-Apr-12 8:32am

Just step through it with a debugger. Should be easy to find the issue.

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Ruselo Riva Asentista · Answer 1 · 2012-04-13T04:14:00

Try adding single quotes to the string.

C#

SqlCommand cmd = new SqlCommand("Delete from FIRrecord where namplc2 ='" + i + "'", abc);

Here: my_data is converted to INT or a column name depending on the database server

SQL

Delete from FIRrecord where namplc2 = my_data

Here: my_data is converted to NVARCHAR

SQL

Delete from FIRrecord where namplc2 = 'my_data'

Despite that, I think your code will have problems because you changed the datagridview rows collection while iterating using the variable i.

The problem is this:
i = 0 firGridView1.Rows.Count = 4
i = 1 firGridView1.Rows.Count = 4
i = 2 firGridView1.Rows.Count = 4 // If this row is for deletion
i = 3 firGridView1.Rows.Count = 3