Oracle PL/SQL REF CURSOR is a datatype used to store a cursor reference in a PL/SQL block. It is a type of data that refers to a cursor, which is essentially a memory area that stores the results of a query.
A REF CURSOR is a named cursor that can be opened and used within a PL/SQL block. It allows you to pass a cursor reference as an argument to a procedure or function, which can then open the cursor and retrieve the data stored in it. This makes it a useful tool for implementing complex data retrieval operations in your PL/SQL applications.
To declare a REF CURSOR, you can use the following syntax:
TYPE cursor_name IS REF CURSOR;
Once declared, you can then open the REF CURSOR and associate it with a query using the OPEN statement:
OPEN cursor_name FOR select_statement;
The query associated with the REF CURSOR can be any valid SQL query that returns a result set. You can then fetch the data from the REF CURSOR using a loop and the FETCH statement:
LOOP FETCH cursor_name INTO ...; EXIT WHEN cursor_name%NOTFOUND; ... END LOOP;
Finally, you can close the REF CURSOR using the CLOSE statement:
Overall, REF CURSOR is a powerful feature of Oracle PL/SQL that allows you to handle complex data retrieval operations and to pass cursor references as arguments to procedures and functions. By using REF CURSORs, you can encapsulate the details of data retrieval and processing within your PL/SQL code, making it easier to maintain and modify your applications over time.