$ java -jar taq.jar asia_top_ten
Running query asia_top_ten in global scope
asia_top_ten(1, city=Tokyo, country=Japan, population=37,900,000)
asia_top_ten(2, city=Delhi, country=India, population=26,580,000)
asia_top_ten(3, city=Seoul, country=South Korea, population=26,100,000)
asia_top_ten(4, city=Shanghai, country=China, population=25,400,000)
asia_top_ten(5, city=Mumbai, country=India, population=23,920,000)
asia_top_ten(6, city=Beijing, country=China, population=21,650,000)
asia_top_ten(7, city=Jakarta, country=Indonesia, population=20,500,000)
asia_top_ten(8, city=Karachi, country=Pakistan, population=20,290,000)
asia_top_ten(9, city=Osaka, country=Japan, population=20,260,000)
asia_top_ten(10, city=Manila, country=Philippines, population=20,040,000)asia_top_ten.taq provides an example of filtering data according to a couple of conditions. In this case we are selecting the ten top Asian cities from a list of 30 highly populated cities from 5 continents. The list is already sorted by population size, so this makes getting the top 10 cities simply a matter of selecting the first 10 cities.
The expression used to filter the incoming cities tests firstly for the continent of Asia and then establishes if the city is one of the first 10
rank ?? Continent == “Asia” && rank++ < 10
Here we see the ?? operator which allows any boolean
expression to be used to test for a condition.
The “rank” variable is of interest because it is both declared as a private integer in the template scope and yet it’s value appears as the first item in each city record returned from the query. The value is inserted in an anonymous term using the term keyword
term rank