sql pulling a row for next or previous row of a current row

Question

id    |  photo title     |  created_date

XEi43 |  my family       |  2009 08 04
dDls  |  friends group   |  2009 08 05
32kJ  |  beautiful place |  2009 08 06
EOIk  |  wo         


        

Answer 1

Using Mike's MAX/MIN trick we can make previous\next jumps for all sorts of things. This msAccess example will return the previous close for every record in a stock market data table. Note: the '<=' is for weekends and holidays.

SELECT 
   tableName.Date,
   tableName.Close,
   (SELECT Close 
      FROM tableName 
      WHERE Date = (SELECT MAX(Date) FROM tableName 
                     WHERE Date <= iJoined.yesterday)
   ) AS previousClose
FROM 
 (SELECT Date, DateAdd("d",-1, Date) AS yesterday FROM tableName)
  AS iJoined 
INNER JOIN 
    tableName ON tableName.Date=iJoined.Date;

...'yesterday' demonstrates using a function(Date-1) jump; we could have simply used...

(SELECT Date FROM tableName) AS iJoined
  /* previous record */
(SELECT MAX(Date) FROM tableName WHERE Date < iJoined.Date)
  /* next record */
(SELECT MIN(Date) FROM tableName WHERE Date > iJoined.Date)

The trick is we can previous\next # of whatever(s) with MAX\MIN and a jump function()