FETCH(7)							   SQL Commands 							  FETCH(7)

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
       particular row of the result, or after the last row of the result. When created, a cursor is positioned before the first row.  After fetch-
       ing 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.

	      Note:  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 in the documentation.

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 current 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.

       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 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 count and FETCH ALL, in which FORWARD is implicit, are Post-
       greSQL 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(7)], MOVE [move(7)]

SQL - Language Statements					    2010-05-14								  FETCH(7)