A cursor is a pointer to this context area. In PL/SQL, the context area is controlled by Cursor. A cursor contains information on a select statement and the rows of data accessed by it. A cursor is used to referred to a program to fetch and process the rows returned by the SQL statement, one at a time.
How many types of cursors are available in PL SQL?
two types
A cursor is a pointer that points to a result of a query. PL/SQL has two types of cursors: implicit cursors and explicit cursors.
Why cursor is used in PL SQL?
The major function of a cursor is to retrieve data, one row at a time, from a result set, unlike the SQL commands which operate on all the rows in the result set at one time. Cursors are used when the user needs to update records in a singleton fashion or in a row by row manner, in a database table.
What is cursor attributes in PL SQL?
Each cursor has a set of attributes that enables an application program to test the state of the cursor. These attributes are %ISOPEN, %FOUND, %NOTFOUND, and %ROWCOUNT. This attribute is used to determine whether a cursor contains rows after the execution of a FETCH statement. …
What is implicit cursor in PL SQL?
Implicit cursors are automatically created by Oracle whenever an SQL statement is executed, when there is no explicit cursor for the statement. For INSERT operations, the cursor holds the data that needs to be inserted. For UPDATE and DELETE operations, the cursor identifies the rows that would be affected.
What is cursor exception Plsql?
In PL/SQL, a warning or error condition is called an exception. When an error occurs, an exception is raised. That is, normal execution stops and control transfers to the exception-handling part of your PL/SQL block or subprogram. Internal exceptions are raised implicitly (automatically) by the run-time system.
What is difference between trigger and cursor?
A cursor is activated and thus created in response to any SQL statement. A trigger is executed in response to a DDL statement, DML statement or any database operation.
How do cursors work in SQL?
SQL Cursor Life Cycle A cursor is declared by defining the SQL statement. A cursor is opened for storing data retrieved from the result set. When a cursor is opened, rows can be fetched from the cursor one by one or in a block to do data manipulation. The cursor should be closed explicitly after data manipulation.
How many types of cursors are there?
There are 2 types of Cursors: Implicit Cursors, and Explicit Cursors. These are explained as following below. Implicit Cursors: Implicit Cursors are also known as Default Cursors of SQL SERVER.
How does cursor work in SQL?
What are PL/SQL cursors in Oracle Database?
Oracle PL/SQL Cursor: Implicit, Explicit, Cursor FOR Loop [Example] Implicit Cursor. Whenever any DML operations occur in the database, an implicit cursor is created that holds the rows affected, in that particular operation. Explicit Cursor. Programmers are allowed to create named context area to execute their DML operations to get more control over it. Cursor Attributes. FOR Loop Cursor statement.
How to close and delete cursor in SQL?
How to Close and Delete Cursor in SQL DECLARE : It is used to define a new cursor. OPEN : It is used to open a cursor FETCH : It is used to retrieve a row from a cursor. CLOSE : It is used to close a cursor. DEALLOCATE : It is used to delete a cursor and releases all resources used by cursor.
Is while loop better than cursor?
Sometimes the justification is that constructing a while loop is simpler and more straightforward than constructing a cursor. Others suggest that a while loop is faster than a cursor because, well, it isn’t a cursor. Of course the underlying mechanics still represent a cursor, it’s just not explicitly stated that way using DECLARE CURSOR.
What is the cursor variable in SQL?
The Four Steps in an SQL Cursor Declare. The Declare step of a cursor is where you specify the name of the cursor and the SQL statement that is used to populate it. Open. The next step is Open, which processes and runs the SQL statement that is mentioned in the Declare section. Fetch. Close.
