CODEWITHSUNDEEP
c#
eMRe
eMRe

Reputation: 3247

How to use foreach loop to edit some rows while populating datatable from sql?

I am trying to populate a data table from a database table. After it is populated i am using asp:GridView to show the data.

The problem is I am trying to edit some rows after it is populated from the database but before binding the data.

I am very new to c# so i cant get it working. My code does not update anything.

private void BindGridviewFileData()
{
    string ConnectionStringName = WebConfigurationManager.ConnectionStrings["LocalConnection"].ConnectionString;
    try
    {
       using (SqlConnection sqlConn = new SqlConnection(ConnectionStringName))
        {
            using (SqlCommand sqlCmd = new SqlCommand())
            {
                sqlCmd.CommandText = "SELECT * FROM VISUALISATION";
                sqlCmd.Connection = sqlConn;
                sqlConn.Open();
                SqlDataReader objDataReader = sqlCmd.ExecuteReader();
                DataTable objDataTable = new DataTable();
                objDataTable.Load(objDataReader);

                foreach (DataRow row in objDataTable.Rows)
                    if (row["lineNumber"] == "1")
                        row["BATCH_NO"] = "new Value";

                gvSubjectDetails.DataSource = objDataTable;
                gvSubjectDetails.DataBind();
                sqlConn.Close();
            }
        }
    }
    catch { }
}

Upvotes: 1

Views: 244

Answers (1)

Marc Gravell
Marc Gravell

Reputation: 1063328

The lineNumber check probably needs to be an int check; note that currently it is actually doing an object check, which only supports reference equality - it will never match, even if the value is a string of "1", because the value from the database will become a different string instance than the interned literal "1" from the code. So, the first check probably needs to be:

if((int)row["lineNumber"] == 1)

You ask in comments how to do this with a string; in that case, quite similarly:

if((string)row["BATCH_NO"] == "some value")

This now works because there is an overloaded == operator for string==string, which does a value based equality test, not a reference-based equality test.

Note: you could also probably use:

if(Equals(row["BATCH_NO"], "some value"))

but I find the earlier version clearer.

Upvotes: 2

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