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31.	What are cursors?
	A cursor is a variable that runs through the tuples of some relation. A cursor contains information on a select statement and the rows of data accessed by it. . A cursor can hold more than one row, but can process only one row at a time. The set of rows the cursor holds is called the active set.

	Posted by Viju. (Apr 26, 2013)
	Whenever a SQL statements is given either at SQL prompt or PL/SQL program it gets processed in a separate temporary memory area which is technically called as a cursor.

32.	What are the types of cursors in PL/SQL?
	There are two types of cursors in PL/SQL :: Implicit cursors Explicit cursors

33.	What is the difference between implicit cursors and explicit cursors?
	Implicit cursors :These are created by default when DML statements like, INSERT, UPDATE, and DELETE statements are executed. They are also created when a SELECT statement that returns just one row is executed. Explicit cursors : They must be created when you are executing a SELECT statement that returns more than one row. Even though the cursor stores multiple records, only one record can be processed at a time, which is called as current row. When you fetch a row the current row position moves to next row.

33.

What is the difference between implicit cursors and explicit cursors?

Implicit cursors :These are created by default when DML statements like, INSERT, UPDATE, and DELETE statements are executed. They are also created when a SELECT statement that returns just one row is executed.
Explicit cursors : They must be created when you are executing a SELECT statement that returns more than one row. Even though the cursor stores multiple records, only one record can be processed at a time, which is called as current row. When you fetch a row the current row position moves to next row.

34.	What is the difference between row locking and table locking?
	Row locks are enabled when a specific row is being modified by a DML statement. Table locks are acquired either explicitly or implicitly when either a row or a table is being modified.

35.	What is data abstraction ?
	PL/SQL supports data abstraction. Data abstraction means the essential properties of the data are provided to the user while ignoring unnecessary details.

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