Cursor in pl/sql.

hello guys in this tutorial we are going to learn the implicit cursor So,

first we under stood that what is the implicit cursor :

       A implicit cursor is the system cursor where all the event are stored in there. the entire place of memory allocation for the Oracle engine is called context area. the context area is contain all the event which are process.

      A cursor is the simple pointer which is only retrive the data from the context area. and all the data(event) are stored in context area in temporally.
      when we closed our sql software then the memory allocation of context area in remove. the main point in our sql system is that

•  DDL(data definition language ) 
•  DML(data manipulate language)

     when we fired any DDL commands then the events are permanently saved and the ROLL BACK command are not worked.

      but when we fired any DML command then we can perform ROLL BACK to backup out DATA. when we fired ROLL BACK then the SQL(implicit cursor) is retrive the data from context are and it Display the ROLL BACK is complete.

           that means the DML events are stored into the context area in temporary. So,the main purpose is the cursor that it retrive the data from the context area.

there are two type of cursor

1. implicit
2. explicit

1.implicit cursor : here we have a table of customer

SQL> select *from customer;

     AC_NO       B_NO NAME       CITY          BALANCE      COUNT CHK_DATE
---------- ---------- ---------- ---------- ---------- ---------- ---------
       111        101 biku       surat            7990          1 02-SEP-19
       112        103 sunil      vapi            11000          1 02-SEP-19
       113        102 balram     valsad          19000          3 01-JAN-19
       114        104 jenna      surat           18000          2 01-JAN-19
       115        105 sagar      mumbai           9000          1 01-JAN-19
       116        101 chirag     surat             800          3 01-JAN-19
       117        102 aditya     vapi              500          5 01-JAN-19
       118        103 rahul      valsad          14000          2 01-JAN-19
       119        103 bhavesh    mumbai           5000          1 01-JAN-19
       120        104 jay        surat             400          4 01-JAN-19
       121        105 bhola      vapi            11000          4 01-JAN-19

     AC_NO       B_NO NAME       CITY          BALANCE      COUNT CHK_DATE
---------- ---------- ---------- ---------- ---------- ---------- ---------
       122        101 mina       valsad           8000          2 01-JAN-19
       123        102 montu      surat            9000          2 01-JAN-19

13 rows selected.

SQL> select *from customer where ac_no=122;

     AC_NO       B_NO NAME       CITY          BALANCE      COUNT CHK_DATE
---------- ---------- ---------- ---------- ---------- ---------- ---------
       122        101 mina       valsad           8000          2 01-JAN-19

And we update the name of mina to sima

update customer set name='sima' where ac_no=122;
1 row updated.

the background process is updated.

declare      
	m_name varchar2(10);
begin 	
	update customer set name='sima' where ac_no=122;
		if sql%found then
		dbms_output.put_line('data is found');
	else	
		dbms_output.put_line('data is not found');
	end if;
end;
/

SQL> @C:\Users\Vibhuti\cursor.sql

data is found



PL/SQL procedure successfully completed.

here the sql cursor is checked that the updated statement is found or not.

if it is found then it return data is found and if the data is not found then it return data is not found.
 So, the implicit cursor is work like above.



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