Using Clause (Part 2)
Introduction Besides the clauses mentioned in the previous article, PostgreSQL, as an exceptionally powerful database management system, supports many other specialized clauses as follows. Navigation and Pagination Group This is a basic yet crucial group that is very widely used. ORDER BY : Sorts the returned results in ascending ( ASC ) or descending ( DESC ) order. There is also ORDER BY col DESC NULLS LAST to push NULL values to the very bottom of the result table instead of the default top when sorting in descending order. LIMIT/OFFSET : Used for pagination. LIMIT N retrieves a maximum of N rows. OFFSET M skips the first M rows before retrieving. When you use OFFSET M , PostgreSQL must still scan and count all the first M rows to know where to begin, then it retrieves the next N rows for LIMIT . The consequence is that if OFFSET is small (for the first pages), the query still runs very fast. If OFFSET is large, such as using OFFSET 100000 , the database must expend resour...