FETCH — retrieve rows from a query using a cursor
FETCH [direction[ FROM | IN ] ]cursor_namewheredirectioncan be empty or one of: NEXT PRIOR FIRST LAST ABSOLUTEcountRELATIVEcountcountALL FORWARD FORWARDcountFORWARD ALL BACKWARD BACKWARDcountBACKWARD ALL
   FETCH retrieves rows using a previously-created cursor.
  
   A cursor has an associated position, which is used by
   FETCH.  The cursor position can be before the first row of the
   query result, on any particular row of the result, or after the last row
   of the result.  When created, a cursor is positioned before the first row.
   After fetching some rows, the cursor is positioned on the row most recently
   retrieved.  If FETCH runs off the end of the available rows
   then the cursor is left positioned after the last row, or before the first
   row if fetching backward.  FETCH ALL or FETCH BACKWARD
   ALL will always leave the cursor positioned after the last row or before
   the first row.
  
   The forms NEXT, PRIOR, FIRST,
   LAST, ABSOLUTE, RELATIVE fetch
   a single row after moving the cursor appropriately.  If there is no
   such row, an empty result is returned, and the cursor is left
   positioned before the first row or after the last row as
   appropriate.
  
   The forms using FORWARD and BACKWARD
   retrieve the indicated number of rows moving in the forward or
   backward direction, leaving the cursor positioned on the
   last-returned row (or after/before all rows, if the count exceeds the number of rows
   available).
  
   RELATIVE 0, FORWARD 0, and
   BACKWARD 0 all request fetching the current row without
   moving the cursor, that is, re-fetching the most recently fetched
   row.  This will succeed unless the cursor is positioned before the
   first row or after the last row; in which case, no row is returned.
  
This page describes usage of cursors at the SQL command level. If you are trying to use cursors inside a PL/pgSQL function, the rules are different — see Section 42.7.
directiondirection defines
      the fetch direction and number of rows to fetch.  It can be one
      of the following:
      
NEXT          Fetch the next row. This is the default if direction is omitted.
         
PRIORFetch the prior row.
FIRST          Fetch the first row of the query (same as ABSOLUTE 1).
         
LAST          Fetch the last row of the query (same as ABSOLUTE -1).
         
ABSOLUTE count          Fetch the count'th row of the query,
          or the abs('th row from
          the end if count)count is negative.  Position
          before first row or after last row if count is out of range; in
          particular, ABSOLUTE 0 positions before
          the first row.
         
RELATIVE count          Fetch the count'th succeeding row, or
          the abs('th prior
          row if count)count is
          negative.  RELATIVE 0 re-fetches the
          current row, if any.
         
count          Fetch the next count rows (same as
          FORWARD ).
         count
ALL          Fetch all remaining rows (same as FORWARD ALL).
         
FORWARD          Fetch the next row (same as NEXT).
         
FORWARD count          Fetch the next count rows.
          FORWARD 0 re-fetches the current row.
         
FORWARD ALLFetch all remaining rows.
BACKWARD          Fetch the prior row (same as PRIOR).
         
BACKWARD count          Fetch the prior count rows (scanning
          backwards).  BACKWARD 0 re-fetches the
          current row.
         
BACKWARD ALLFetch all prior rows (scanning backwards).
countcount is a
      possibly-signed integer constant, determining the location or
      number of rows to fetch.  For FORWARD and
      BACKWARD cases, specifying a negative count is equivalent to changing
      the sense of FORWARD and BACKWARD.
     
cursor_nameAn open cursor's name.
   On successful completion, a FETCH command returns a command
   tag of the form
FETCH count
   The count is the number
   of rows fetched (possibly zero).  Note that in
   psql, the command tag will not actually be
   displayed, since psql displays the fetched
   rows instead.
  
   The cursor should be declared with the SCROLL
   option if one intends to use any variants of FETCH
   other than FETCH NEXT or FETCH FORWARD with
   a positive count.  For simple queries
   PostgreSQL will allow backwards fetch
   from cursors not declared with SCROLL, but this
   behavior is best not relied on. If the cursor is declared with
   NO SCROLL, no backward fetches are allowed.
  
   ABSOLUTE fetches are not any faster than
   navigating to the desired row with a relative move: the underlying
   implementation must traverse all the intermediate rows anyway.
   Negative absolute fetches are even worse: the query must be read to
   the end to find the last row, and then traversed backward from
   there.  However, rewinding to the start of the query (as with
   FETCH ABSOLUTE 0) is fast.
  
DECLARE is used to define a cursor. Use MOVE to change cursor position without retrieving data.
The following example traverses a table using a cursor:
BEGIN WORK; -- Set up a cursor: DECLARE liahona SCROLL CURSOR FOR SELECT * FROM films; -- Fetch the first 5 rows in the cursor liahona: FETCH FORWARD 5 FROM liahona; code | title | did | date_prod | kind | len -------+-------------------------+-----+------------+----------+------- BL101 | The Third Man | 101 | 1949-12-23 | Drama | 01:44 BL102 | The African Queen | 101 | 1951-08-11 | Romantic | 01:43 JL201 | Une Femme est une Femme | 102 | 1961-03-12 | Romantic | 01:25 P_301 | Vertigo | 103 | 1958-11-14 | Action | 02:08 P_302 | Becket | 103 | 1964-02-03 | Drama | 02:28 -- Fetch the previous row: FETCH PRIOR FROM liahona; code | title | did | date_prod | kind | len -------+---------+-----+------------+--------+------- P_301 | Vertigo | 103 | 1958-11-14 | Action | 02:08 -- Close the cursor and end the transaction: CLOSE liahona; COMMIT WORK;
   The SQL standard defines FETCH for use in
   embedded SQL only.  The variant of FETCH
   described here returns the data as if it were a
   SELECT result rather than placing it in host
   variables.  Other than this point, FETCH is
   fully upward-compatible with the SQL standard.
  
   The FETCH forms involving
   FORWARD and BACKWARD, as well
   as the forms FETCH  and countFETCH
   ALL, in which FORWARD is implicit, are
   PostgreSQL extensions.
  
   The SQL standard allows only FROM preceding the cursor
   name; the option to use IN, or to leave them out altogether, is
   an extension.