Returns an ordered ranking of rows based on the value_expression in the ORDER BY clause.
All rows having the same value_expression value are assigned the same rank.
If n rows have the same value_expression values, then they are assigned the same rank, call it rank r. The next distinct value receives rank r +n. And so on.
Less formally, RANK sorts a result set and identifies the numeric rank of each row in the result. RANK returns an integer that represents the rank of each row in the result.
To use this function with time series data, see Teradata Vantage™ - Time Series Tables and Operations, B035-1208.
ANSI SQL:2011 window function.