[c#] Best way to check if a Data Table has a null value in it

what is the best way to check if a Data Table has a null value in it ?

Most of the time in our scenario, one column will have all null values.

(This datatable is returned by a 3rd party application - we are trying to put a valiadation before our application processes the data-table)

foreach(DataRow row in dataTable.Rows)
{
    if(row.IsNull("myColumn"))
        throw new Exception("Empty value!")
}

You can null/blank/space Etc value using LinQ Use Following Query

   var BlankValueRows = (from dr1 in Dt.AsEnumerable()
                                  where dr1["Columnname"].ToString() == ""
                                  || dr1["Columnname"].ToString() == ""
                                   || dr1["Columnname"].ToString() == ""
                                  select Columnname);

Here Replace Columnname with table column name and "" your search item in above code we looking null value.

I will do like....

(!DBNull.Value.Equals(dataSet.Tables[6].Rows[0]["_id"]))

You can loop throw the rows and columns, checking for nulls, keeping track of whether there's a null with a bool, then check it after looping through the table and handle it.

//your DataTable, replace with table get code
DataTable table = new DataTable();
bool tableHasNull = false;

foreach (DataRow row in table.Rows)
{
    foreach (DataColumn col in table.Columns)
    {
        //test for null here
        if (row[col] == DBNull.Value)
        {
            tableHasNull = true;
        }
    }
}

if (tableHasNull)
{
    //handle null in table
}

You can also come out of the foreach loop with a break statement e.g.

//test for null here
if (row[col] == DBNull.Value)
{
    tableHasNull = true;
    break;
}

To save looping through the rest of the table.

DataTable dt = new DataTable();
foreach (DataRow dr in dt.Rows)
{
    if (dr["Column_Name"] == DBNull.Value)
    {
        //Do something
    }
    else
    {
        //Do something
    }
}