Sql Queries

[beechy34]

hi im looking at some exam examples and i just want to know if im doing it right, here it is.1. Assume Sales is a relational table with schemaSales(year, month, city, category, customers, units)that contains aggregate data such as the number of customers and the units sold of a given product category at a particular month and year. Write SQL queries that make use of Oracle 10g analytical functions to answer the following questions:a) Rank the sales data (in descending order) per city according to units sold.] Rank the sales data (in ascending order) per year and month, according to the number of customers.for a i did this

select*from(select rank()over (order by units desc) rnk, year, month, city, category, customers, units  from salesgroup by city)

and for b i did this

select*from(select rank()over (order by customers asc) rnk, year, month, city, category, customers. units  from salesgroup by month, city)

i dont think they are right, can you tell me how to do them properly thankyou