FETCH(7)		PostgreSQL 9.2.24 Documentation		      FETCH(7)



NAME
       FETCH - retrieve rows from a query using a cursor

SYNOPSIS
       FETCH [ direction [ FROM | IN ] ] cursor_name

       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 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.

	   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 Section 39.7, "Cursors", 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.

       cursor_name
	   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
       displays 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(7) is used to define a cursor. Use 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 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.

SEE ALSO
       CLOSE(7), DECLARE(7), MOVE(7)



PostgreSQL 9.2.24		  2017-11-06			      FETCH(7)