Oracle PL/SQL Tutorial/Transaction/Transaction Level

Set the transaction isolation level using the SET TRANSACTION statement.

SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;

set transaction isolation level read committed;

begin
    set transaction isolation level read committed;
end;
/
SQL>
SQL>

set transaction isolation level to serializable in PL/SQL

Declare
    v_nr NUMBER;
Begin
   set transaction isolation level serializable;
End;
/

SET TRANSACTION READ WRITE

SQL> CREATE TABLE project (
  2    pro_id              NUMBER(4),
  3    pro_name            VARCHAR2(40),
  4    budget          NUMBER(9,2),
  5    CONSTRAINT project_pk   PRIMARY KEY (pro_id)
  6  );
Table created.
SQL>
SQL>
SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1001, "A",12345);
1 row created.
SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1002, "ERP",23456);
1 row created.
SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1003, "SQL",34567);
1 row created.
SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1004, "CRM",45678);
1 row created.
SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1005, "VPN",56789);
1 row created.
SQL>
SQL>
SQL> CREATE TABLE server_usage (
  2    pro_id                   NUMBER(4),
  3    emp_id                  NUMBER,
  4    time_log_date                DATE,
  5    hours_logged                 NUMBER(8,2),
  6    dollars_charged              NUMBER(8,2),
  7    CONSTRAINT server_usage_pk  PRIMARY KEY (pro_id, emp_id, time_log_date)
  8  );
Table created.
SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged)
  2                    VALUES (1001,101,to_date("4-Apr-2004","dd-mon-yyyy"),1123,222);
1 row created.
SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged)
  2                    VALUES (1002,102,to_date("4-Apr-2005","dd-mon-yyyy"),1124,223);
1 row created.
SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged)
  2                    VALUES (1003,103,to_date("4-Apr-2006","dd-mon-yyyy"),1125,224);
1 row created.
SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged)
  2                    VALUES (1004,104,to_date("4-Apr-2007","dd-mon-yyyy"),1126,225);
1 row created.
SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged)
  2                    VALUES (1005,105,to_date("4-Apr-2008","dd-mon-yyyy"),1127,226);
1 row created.
SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged)
  2                    VALUES (1001,106,to_date("4-Apr-2009","dd-mon-yyyy"),1128,227);
1 row created.
SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged)
  2                    VALUES (1002,107,to_date("4-Apr-2010","dd-mon-yyyy"),1129,228);
1 row created.
SQL> SET ECHO ON
SQL> 
SQL> SET TRANSACTION READ WRITE;
SQL>
SQL> 
SQL> INSERT INTO project
  2     SELECT 2008, pro_name, budget FROM project
  3     WHERE pro_id = 1002;
1 row created.
SQL>
SQL> 
SQL> UPDATE server_usage
  2  SET pro_id = 2008
  3  WHERE pro_id = 1002;
2 rows updated.
SQL>
SQL> 
SQL> ROLLBACK;
Rollback complete.
SQL>
SQL>
SQL> drop table project;
Table dropped.
SQL> drop table server_usage;
Table dropped.