A cursor is a working area where an SQL statement is executed. It is used to process individual rows returned by the database system for a query.
There are two types of cursor
- Implicit cursor: It is a predefined cursor that is associated with DML hence the declaration is not required in this cursor. Some of the attributes used as implicit cursors are %FOUND, %NOT FOUND, %OPEN, %ROWCOUNT.
- Explicit cursor: It is a user-defined cursor hence the declaration is required for this cursor. It is associated with the SELECT statement of SQL which returns more than one row. The associated commands used are DECLARE, OPEN, CLOSE, FETCH, etc.
Various cursor attributes
|%FOUND||Returns true if the DML statement affects at least one row else returns false.|
|%NOT FOUND||Returns true if no row is affected by the DML statement else returns false|
|%OPEN||Returns false implicit function or explicit function is close and returns true if the explicit function is open.|
|%ROWCOUNT||Returns the number of affected rows|
|DECLARE||Used to declare the curser in declare section|
|OPEN||Used to open the cursor in the execution section|
|CLOSE||Used to close the cursor in the execution section before the end of PL/SQL.|
|FETCH||Used to fetch the data from the cursor|
Now let’s have a look at the example
DECLARE C_id customer.id C_name customer.name Cursor C1 IS SELECT id, name from customer; BEGIN OPEN C1 LOOP FETH C1 INTO C_id, C_name; EXIT WHEN C1%NOTFOUND; Dbms.output.put_line(“id:=”||C_id||”name:=”||C_name); END LOOP; CLOSE C1; END; /