NAME

       FETCH - retrieve rows from a query using a cursor

SYNOPSIS

       FETCH [ direction ] [ FROM | IN ] cursor_name

       where direction can
       be 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 42.7.3.

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)