how to check null values in dataset?

for(------)
{
if(ds.tables[0].Rows[i]["columnname"].tostring()!=null)
{
}
else
{
}
}

you can do it like this:


DataTable dt = ds.Tables[0];
        foreach (DataRow row in dt.Rows)
        {
            object value = row["ColumnName"];
            if (value == DBNull.Value)
            {
                // do something
            }
            else
            {
                // do something else
            }
        }

pass the column name to search