How to split the datatable column name into two columns based on positive values and negative values in ASP.NET

//source datatable
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[]
	{
		new DataColumn("Id", typeof(int)), 
		new DataColumn("Name", typeof(string)), 
		new DataColumn("AdvCredit", typeof(int))
	});
dt.Rows.Add(new object[]{1, "A", -2});
dt.Rows.Add(new object[]{2, "B", 1});
dt.Rows.Add(new object[]{3, "c", -9});
dt.Rows.Add(new object[]{4, "d", 4});

//create destination datatable based on source datatable
DataTable dstdt = dt.Clone();
//add new column
dstdt.Columns.Add(new DataColumn("AdvCredit1", typeof(int)));
//allow nulls!
dstdt.Columns[2].AllowDBNull = true;
dstdt.Columns[3].AllowDBNull = true;

//default value when condition does not meet
int? defVal = null;
//copy data from source to destination datatable
dstdt = dt.AsEnumerable()
	.Select(x=> dstdt.LoadDataRow(new object[]
	{
		x.Field<int>("Id"),
		x.Field<string>("Name"),
		x.Field<int>("AdvCredit") < 0 ? x.Field<int>("AdvCredit") : defVal,
		x.Field<int>("AdvCredit") > 0 ? x.Field<int>("AdvCredit") : defVal,
	}, false))
	.CopyToDataTable();