Re: get first and last row in one sql as two columns

Rob Sargent <robjsargent@xxxxxxxxx> · Wed, 2 Sep 2015 17:30:13 -0600



    On 09/02/2015 05:14 PM, Tom Smith
      wrote:

    
                    Hi:

                      
                    I need to get the first and last tow in one sql like
                    below

                    
                  select first(col1), last(col1) from table order by
                  col1

                  
                I saw some posting in wiki with a custom function (or C
                extention)

              
              to do this.   Is it widely used and reliable?

              https://wiki.postgresql.org/wiki/First/last_(aggregate)

              
            I am wondering why these two functions are not part of
            postgresql built-in

          
          functions as it has many use cases

          
        Thanks

      
    But what I think you
      are looking for are the windowing functions as what you propose
      breaks down pretty quickly with more complicated queries.