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FETCH()				 SQL Commands			       FETCH()



NAME
       FETCH - retrieve rows from a query using a cursor


SYNOPSIS
       FETCH [ direction { FROM | IN } ] cursorname

       where direction can be empty or one of:

	   NEXT
	   PRIOR
	   FIRST
	   LAST
	   ABSOLUTE count
	   RELATIVE count
	   count
	   ALL
	   FORWARD
	   FORWARD count
	   FORWARD ALL
	   BACKWARD
	   BACKWARD count
	   BACKWARD ALL


DESCRIPTION
       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  par-
       ticular	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.

PARAMETERS
       direction
	      direction	 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.

	      PRIOR  Fetch 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(count)'th
		     row from the end if 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(count)'th
		     prior row if 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 cur-
		     rent row.

	      FORWARD ALL
		     Fetch 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 ALL
		     Fetch all prior rows (scanning backwards).


       count  count 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.

       cursorname
	      An open cursor's name.

OUTPUTS
       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 dis-
       plays the fetched rows instead.

NOTES
       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.

       Updating data via a cursor is currently not supported by PostgreSQL.

       DECLARE [declare(7)] is used to define a cursor. Use MOVE [move(7)]  to
       change cursor position without retrieving data.

EXAMPLES
       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;


COMPATIBILITY
       The  SQL standard defines FETCH for use in embedded SQL only. The vari-
       ant 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 count and FETCH ALL, in which FORWARD is implicit, are PostgreSQL
       extensions.

       The SQL standard allows only FROM preceding the cursor name; the option
       to use IN is an extension.

SEE ALSO
       CLOSE [close(7)], DECLARE [declare(l)], MOVE [move(l)]



SQL - Language Statements	  2010-12-14			       FETCH()
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