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+# UNIQUE -- Find unique rows in a table
+#
+# First, the table is sorted on columns input in the colptr array. The
+# results are stored in the index array. Then each row in the index array
+# is compared to the most recent unique row in the index array, column by
+# column. If any column differs, the row is also considered to be unique.
+# The index array is updated to reflect the new unique row and the number of
+# unique rows is incremented.
+#
+# B.Simon	19-Oct-87	First Code
+# B.Simon	14-Dec-87	Changed to handle table subsets
+# B.Simon	06-Feb-90	Changed to use tbtsrt and tbrcmp
+
+procedure unique (tp, numptr, colptr, nindex, index)
+
+pointer	tp		#  i: Table descriptor
+int	numptr		#  i: Number of column pointers
+pointer	colptr[ARB]	#  i: Array of column pointers
+int	nindex		# io: Number of unique row indices returned
+int	index[ARB]	# io: Array of unique indices
+#--
+bool	fold
+int	order, idx, jdx, n, i
+
+int	tbrcmp()
+
+begin
+
+	# Sort the array on the selected columns. The sort is in ascending
+	# order and case sensitive
+
+	fold = false
+	call tbtsrt (tp, numptr, colptr, fold, nindex, index)
+
+	# Search for unique rows
+
+	jdx = 0
+	n = nindex
+	nindex = 0
+
+	do i = 1, n {
+	    idx = index[i]
+
+	    # First row is always unique
+
+	    if (i == 1)
+		order = 1
+	    else
+		order = tbrcmp (tp, numptr, colptr, fold, idx, jdx)
+
+	    # Update pointer to most recent unique row and modify index
+	    # array in place
+
+	    if (order != 0) {
+		jdx = idx
+		nindex = nindex + 1
+		index[nindex] = idx
+	    }
+	}
+
+	do i = nindex+1, n
+	    index[i] = 0
+
+end