lookup(dataset, lookupValue, noMatchValue[, lookupColumn][, resultColumn])
DataSet dataset - A dataset to search through.
object lookupValue - The value to look for.
object noMatchValue - The result value if no match.
object lookupColumn - Optional. The column to lookup. Can either be the column index or the name of the column.
object resultColumn - Optional. The column to pull the result value from. Can either be the column index or the name of the column.
object - The value in the result column of the same row that the lookupValue was found, or the noMatchValue if a match was not found.