In X++ we can use System.Data.SqlClient.SqlReader or System.Data.DataSet, to Query on external database. But unfortunately there is No isDBNull function available for checking the null and same time system.string().isnullorempty and CLRInterop::Null is not work.
If you are using dataset or datatable then use datarow’s is null method
For example
If (!DataRow.isNull(“FirstName”)
{
Info(DataRow.get_Item(“FirstName”);
}
Second way to use the index of column according to field name in query, It is zero based index
If (!DataRow.isNull(0)
{
Info(DataRow.get_Item(“FirstName”);
}
If use data reader then use data reader is dbnull method, this method takes the index of field, there is no overload method for field Name,
int columnNum = datareader.GetOrdinal(“FirstName”);
if (datareader.IsDBNull(columnNum))
{
Info(datareader.get_item(“FirstName”);}