Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages

RedHat 9 (Linux i386) - man page for fetch (redhat section 7)

FETCH(7)				   SQL Commands 				 FETCH(7)

NAME
       FETCH - retrieve rows from a table using a cursor

SYNOPSIS
       FETCH [ direction ] [ count ] { IN | FROM } cursor
       FETCH [ FORWARD | BACKWARD | RELATIVE ] [ # | ALL | NEXT | PRIOR ]
	   { IN | FROM } cursor

   INPUTS
       direction
	      selector defines the fetch direction. It can be one of the following:

	      FORWARD
		     fetch next row(s). This is the default if selector is omitted.

	      BACKWARD
		     fetch previous row(s).

	      RELATIVE
		     Noise word for SQL92 compatibility.

       count  count determines how many rows to fetch. It can be one of the following:

	      #      A	signed	integer that specifies how many rows to fetch.	Note that a nega-
		     tive integer is equivalent to changing the sense of FORWARD and BACKWARD.

	      ALL    Retrieve all remaining rows.

	      NEXT   Equivalent to specifying a count of 1.

	      PRIOR  Equivalent to specifying a count of -1.

       cursor An open cursor's name.

   OUTPUTS
       FETCH returns the results of the query defined by the  specified  cursor.   The	following
       messages will be returned if the query fails:

       WARNING: PerformPortalFetch: portal "cursor" not found
	      If  cursor is not previously declared.  The cursor must be declared within a trans-
	      action block.

       WARNING: FETCH/ABSOLUTE not supported, using RELATIVE
	      PostgreSQL does not support absolute positioning of cursors.

       ERROR: FETCH/RELATIVE at current position is not supported
	      SQL92 allows one to repetitively retrieve the cursor at  its  ``current  position''
	      using the syntax

	      FETCH RELATIVE 0 FROM cursor.

	      PostgreSQL  does	not  currently	support  this  notion;	in fact the value zero is
	      reserved to indicate that all rows should be retrieved and is equivalent to  speci-
	      fying  the  ALL keyword.	If the RELATIVE keyword has been used, PostgreSQL assumes
	      that the user intended SQL92 behavior and returns this error message.

DESCRIPTION
       FETCH allows a user to retrieve rows using a cursor.  The  number  of  rows  retrieved  is
       specified  by  #.  If the number of rows remaining in the cursor is less than #, then only
       those available are fetched.  Substituting the keyword ALL in place of a number will cause
       all  remaining  rows in the cursor to be retrieved.  Instances may be fetched in both FOR-
       WARD and BACKWARD directions. The default direction is FORWARD.

	      Tip: Negative numbers are allowed to be specified for the  row  count.  A  negative
	      number  is  equivalent to reversing the sense of the FORWARD and BACKWARD keywords.
	      For example, FORWARD -1 is the same as BACKWARD 1.

   NOTES
       Note that the FORWARD and BACKWARD keywords are PostgreSQL extensions.  The  SQL92  syntax
       is  also  supported, specified in the second form of the command. See below for details on
       compatibility issues.

       Updating data in a cursor is not supported by PostgreSQL, because mapping  cursor  updates
       back  to  base  tables  is  not generally possible, as is also the case with VIEW updates.
       Consequently, users must issue explicit UPDATE commands to replace data.

       Cursors may only be used inside of transactions because the data  that  they  store  spans
       multiple user queries.

       Use  MOVE [move(7)] to change cursor position.  DECLARE [declare(7)] will define a cursor.
       Refer to BEGIN [begin(7)], COMMIT [commit(7)],  and  ROLLBACK  [rollback(7)]  for  further
       information about transactions.

USAGE
       The following examples traverses a table using a cursor.

       -- Set up and use a cursor:

       BEGIN WORK;
       DECLARE liahona CURSOR FOR SELECT * FROM films;

       -- Fetch first 5 rows in the cursor liahona:
       FETCH FORWARD 5 IN 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 previous row:
       FETCH BACKWARD 1 IN liahona;

	code  | title	| did | date_prod  | kind   | len
       -------+---------+-----+------------+--------+-------
	P_301 | Vertigo | 103 | 1958-11-14 | Action | 02:08

       -- close the cursor and commit work:

       CLOSE liahona;
       COMMIT WORK;

COMPATIBILITY
   SQL92
	      Note:  The  non-embedded	use  of cursors is a PostgreSQL extension. The syntax and
	      usage of cursors is being compared against the embedded form of cursors defined  in
	      SQL92.

       SQL92  allows absolute positioning of the cursor for FETCH, and allows placing the results
       into explicit variables:

       FETCH ABSOLUTE #
	   FROM cursor
	   INTO :variable [, ...]

       ABSOLUTE
	      The cursor should be positioned to the specified absolute row number. All row  num-
	      bers in PostgreSQL are relative numbers so this capability is not supported.

       :variable
	      Target host variable(s).

SQL - Language Statements		    2002-11-22					 FETCH(7)


All times are GMT -4. The time now is 06:52 PM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
UNIX.COM Login
Username:
Password:  
Show Password