Cursors in Oracle Explanation with Example

A cursor is a handle (pointer) in memory for a DML operation (Select Update).

There are mainly 2 types of cursors .
1) Implicit Cursor.
2) Explicit Cursor.

Implicit cursor: Oracle will implicitly creates an area for the DML operations. Programmer will not have control on implicit cursors. The only useful attribute on this implicit cursor is SQL ROWCOUNT it will give the number of rows affected by the recent DML operation.

The only Implicit cursor is SQL.

Explicit Cursor:
Explicit cursors are created by the programmer and programmer have control on it
Programmer can

1) Open
2) Fetch
3) Close

and do some manipulations on the values

Explicit Cursors are classified into

1) Normal cursor

2) Parameterized cursor

3) Cursor For Loops and

4) REF cursors

REF Cursors:

Normally when we create a normal cursor we cant change the select query associated to that query (the query which is given at the time of definition)

But using REF cursors we can change the cursor statement also.

These REF cursors are useful when we are sending data from one environment to another environment.