use this String.Join(",", dt.asenumerable.select(function(row) row.Field(of Integer)("Test")).ToList)
Example
result using write line
Note if the above code doesnt work , just change Integer to String String.Join(",", dt.asenumerable.select(function(row) row.Field(of String)("Test")).ToList)
and does the values in your datatable contain commas? if it does do this String.Join(",", dt.asenumerable.select(function(row) row.Field(of String)("Test").Replace(",", "")).ToList)
or this to replace , , with , String.Join(",", dt.asenumerable.select(function(row) row.Field(of String)("Test")).ToList).Replace(",,","")