更新gridview后，用户输入在列中为空白

Question

After I click update in the grid view, the code works successfully. But when I retrieve the data in another webpage the columns I updated are blank. I have no clue why this happens. Here is the code for both updating and displaying: this is for updating

 protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
         string v =     System.Configuration.ConfigurationManager.ConnectionStrings["harish"].ConnectionString;
         con = new OracleConnection(v);
         con.Open();

         string query = "update leave_module1 set name='"+GridView1.Rows[e.RowIndex].Cells[0].Text+"'";
         OracleCommand cmd = new OracleCommand(query, con);
         cmd.ExecuteNonQuery();
         ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script language='javascript'>alert('The Data has been added');</script>;");
         GridView1.EditIndex = -1;
         con.Close();    
}

and this the loadgrid()

   protected void loadgrid()
{

     string v = System.Configuration.ConfigurationManager.ConnectionStrings["harish"].ConnectionString;
        con = new OracleConnection(v);
        con.Open(); 
        cmd = new OracleCommand("select *  from leave_module1 where '"+TextBox1.Text+"' between fd and td", con);
        dr = cmd.ExecuteReader();

        GridView1.DataSource=dr;
        GridView1.DataBind();
        con.Close();
        dr.Close();

}

Answer 1

You haven't mentioned any where clause in your update query , Query should be like this

Update tableName set ColumnName = 'Value'
where IDcolumn = 1

secondly you should work on Stored procedures instead of this approach.

Blank column record must be because your code ( GridView1.Rows[e.RowIndex].Cells[0].Text ) is providing blank data, you should check it by debugging & watching it's value at runtime.

Answer 2

your update statement has no where clause, so will update all of the rows in the table. That might be what you want, might not.

your select statement may also be syntactically flawed. it would only successfully return rows where there is a column with the name of the value of TextBox1.Text that contains a value between the value in a column called fd and the value in a column called td .

Answer 3

These are the might be possible solutions or part of the whole solutions that I think would be helpful:

• Check that loadgrid() isn't called before row_updating event because it will then cause the grid to lose changes and come back to normal view..
• Also check n understand from this link: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.rowupdating.aspx
• Don't keep sql query or connection string name coded in page behind, instead use stored procedure or use some class containing string constants accessible which are thru out solution.
• Always use sql parameter and stop using string concats because it will cause sql infection issues.

Answer 4

When the page is post back the values of the gridviews flushed. If you want to retain the values in Gridview you have to put these values in Viewstate for further operations. you have to use Viewstate.add() for adding your Gridview values in viewstate before postback. viewstate.add("key",value);

Hope it helps you.