Use the OPEN command before using the cursor designated by the DECLARE CURSOR command.
Options
cursor
Specifies a 1 to 18 character cursor name that has been previously specified by the DECLARE CURSOR command.
RESET
Reopens a cursor with the current values of any variables referenced in the DECLARE CURSOR statement. This improves performance by eliminating the need to re-optimize the query.
About the OPEN Command
OPEN evaluates the SELECT clause of the DECLARE CURSOR command using the current values of any variables that it contains. Then OPEN stores that copy of the cursor definition and places the cursor before the first row.
After you close a cursor with the CLOSE command, you can reopen it by repeating the OPEN command. Every time you open a cursor, R:BASE reads the rows again, so that any changes you previously made through the cursor are visible when you look at the rows.
You can display all currently defined cursors with the LIST CURSOR command.
When using the RESET option, the WHERE clause is evaluated with the current values of any referenced variables, and the cursor is reopened without requiring a CLOSE command. The cursor is positioned at the beginning of the result set when the FETCH command is run.
Example
The following command lines show the OPEN command with the RESET option.
DROP CURSOR c1
DROP CURSOR c2
SET VAR vc1custid INTEGER
DECLARE c1 CURSOR FOR SELECT custid FROM customer
-- Selects the transaction rows for the customer
DECLARE c2 CURSOR FOR SELECT transid, invoicetotal +
FROM transmaster WHERE custid = .vc1custid
-- Process the query in cursor c1 and get the first custid
OPEN c1
FETCH c1 INTO vc1custid IND c1ind1
WHILE sqlcode <> 100 THEN
-- Process the query in c2. As each row is fetched in the
-- customer table, the custid changes; each time
-- the "OPEN c2 RESET command" processes the c2's query it
-- retrieves different rows
OPEN c2 RESET
-- Fetch the transid (invoicenumber) and invoice total amount
FETCH c2 into vtransid, vamt
WHILE sqlcode <> 100 THEN
WRITE .vtransid, .vamt
FETCH c2 into vtransid, vamt
ENDWHILE
FETCH c1 INTO vc1custid
ENDWHILE
CLOSE c1
CLOSE c2
DROP CURSOR c1
DROP CURSOR c2
For other examples of the OPEN command, see the DECLARE CURSOR entry.
