FETCH statement [ESQL] [SP]

Description

Repositions a cursor and gets data from it.

Syntax

FETCH
{ NEXT | PRIOR | FIRST | LAST
| ABSOLUTE row-count | RELATIVE row-count }
... cursor-name
... { [ INTO host-variable-list ]
| USING DESCRIPTOR sqlda-name
| INTO variable-list }
... [ PURGE ] [ BLOCK n ] [ ARRAY fetch-count ]
... INTO variable-list
... IQ CACHE row-count

Parameters

Examples

Example 1

• An Embedded SQL example:

EXEC SQL DECLARE cur_employee CURSOR FOR
SELECT emp_id, emp_lname FROM employee ;
EXEC SQL OPEN cur_employee;
EXEC SQL FETCH cur_employee
INTO :emp_number, :emp_name:indicator;

Example 2

• A procedure example:

BEGIN
	DECLARE cur_employee CURSOR FOR
		SELECT emp_lname
		FROM employee ;
	DECLARE name CHAR(40) ;
	OPEN cur_employee;
	LOOP
		FETCH NEXT cur_employee into name ;
		 ...
	END LOOP
	CLOSE cur_employee;
END

Usage

FETCH retrieves one row from the named cursor.

The ARRAY clause allows wide fetches, which retrieve more than one row at a time, and which might improve performance.

The cursor must have been previously opened.

One row from the result of SELECT is put into the variables in the variable list. The correspondence from the select list to the host variable list is one-to-one.

One or more rows from the result of SELECT are put either into the variables in the variable list or into the program data areas described by the named SQLDA. In either case, the correspondence from the select list to either the host variable list or the SQLDA descriptor array is one-to-one.

The INTO clause is optional. If it is not specified, then FETCH positions the cursor only (see the following paragraphs).

An optional positional parameter can be specified that allows the cursor to be moved before a row is fetched. The default is NEXT, which causes the cursor to be advanced one row before the row is fetched. PRIOR causes the cursor to be backed up one row before fetching.

RELATIVE positioning is used to move the cursor by a specified number of rows in either direction before fetching. A positive number indicates moving forward and a negative number indicates moving backwards. Thus, a NEXT is equivalent to RELATIVE 1 and PRIOR is equivalent to RELATIVE -1. RELATIVE 0 retrieves the same row as the last fetch statement on this cursor.

The following clauses are for use in Embedded SQL only:

• USING DESCRIPTOR sqlda-name

• INTO host-variable-list

• PURGE

• BLOCK n

• ARRAY fetch-count

• Use of host-variable in cursor-name and row-count.

DECLARE CURSOR must appear before FETCH in the C source code, and the OPEN statement must be executed before FETCH. If a host variable is being used for the cursor name, then the DECLARE statement actually generates code and thus must be executed before FETCH.

In the multiuser environment, rows can be fetched by the client more than one at a time. This is referred to as block fetching or multirow fetching. The first fetch causes several rows to be sent back from the server. The client buffers these rows and subsequent fetches are retrieved from these buffers without a new request to the server.

The BLOCK clause gives the client and server a hint as to how many rows may be fetched by the application. The special value of 0 means the request is sent to the server and a single row is returned (no row blocking).

The PURGE clause causes the client to flush its buffers of all rows and then send the fetch request to the server. This fetch request may return a block of rows.

If the SQLSTATE_NOTFOUND warning is returned on the fetch, then the sqlerrd[2] field of the SQLCA (SQLCOUNT) contains the number of rows that the attempted fetch exceeded the allowable cursor positions. (A cursor can be on a row, before the first row or after the last row.) The value is 0 if the row was not found but the position is valid, for example, executing FETCH RELATIVE 1 when positioned on the last row of a cursor. The value is positive if the attempted fetch was further beyond the end of the cursor, and negative if the attempted fetch was further before the beginning of the cursor.

After successful execution of the FETCH statement, the sqlerrd[1] field of the SQLCA (SQLIOCOUNT) is incremented by the number of input/output operations required to perform the fetch. This field is actually incremented on every database statement.

To use wide fetches in Embedded SQL, include the FETCH statement in your code as follows:

EXEC SQL FETCH . . . ARRAY nnn

where ARRAY nnn is the last item of the FETCH statement. The fetch count nnn can be a host variable. The SQLDA must contain nnn * (columns per row) variables. The first row is placed in SQLDA variables 0 to (columns per row)-1, and so on.

The server returns in SQLCOUNT the number of records fetched and always returns a SQLCOUNT greater than zero unless there is an error. Older versions of the server only return a single row and the SQLCOUNT is set to zero. Thus a SQLCOUNT of zero with no error condition indicates one valid row has been fetched.

None.

Standards

Permissions

The cursor must be opened and the user must have SELECT permission on the tables referenced in the declaration of the cursor.

See also