Using savepoint, PL-SQL Programming

Assignment Help:

Using SAVEPOINT

The SAVEPOINT names and marks the present point in the processing of a transaction. Used with the ROLLBACK TO statement, the savepoints undo parts of a transaction rather than the entire transaction. In the illustration below, you mark a savepoint before doing an insert. When the INSERT statement tries to store a duplicate value in the empno column, the predefined exception DUP_VAL_ON_INDEX is raised. In that situation, you roll back to the savepoint, undoing merely the insert.

DECLARE

emp_id emp.empno%TYPE;

BEGIN

UPDATE emp SET ... WHERE empno = emp_id;

DELETE FROM emp WHERE ...

...

SAVEPOINT do_insert;

INSERT INTO emp VALUES (emp_id, ...);

EXCEPTION

WHEN DUP_VAL_ON_INDEX THEN

ROLLBACK TO do_insert;

END;

If you roll back to a savepoint, any savepoints marked after the savepoint are erasing. Though, the savepoint to which you roll back is not erasing. For illustration, if you mark five savepoints, and then roll back to the third, only the fourth and the fifth are erase. A simple rollback or commit erases all savepoints.

When you mark a savepoint within a recursive subprogram, the new instances of the

SAVEPOINT statements are executed at each level in the recursive fall. Though, you can only roll back to the nearly all recently marked savepoint.

The Savepoint names are undeclared identifiers and can be reused within the transaction. This moves the savepoint from its old position to the persent point in the transaction. And hence, the rollback to the savepoint affects only the present part of your transaction. An illustration is as shown:

BEGIN

...

SAVEPOINT my_point;

UPDATE emp SET ... WHERE empno = emp_id;

...

SAVEPOINT my_point; -- move my_point to current point

INSERT INTO emp VALUES (emp_id, ...);

EXCEPTION

WHEN OTHERS THEN

ROLLBACK TO my_point;

END;

The number of active savepoints per session is limitless. An active savepoint is the one marked as the last commit or rollback.


Related Discussions:- Using savepoint

Assignment source not a literal - variable, Assignment Source Not a Literal...

Assignment Source Not a Literal - Variable Syntax: SET SN = SID (SUBSTRING (SN.C FROM 1 FOR 1)||'5');

Example of when or then constraints - sql, Example of WHEN or THEN Constrai...

Example of WHEN or THEN Constraints A concrete example showing how SQL supports WHEN/THEN constraints CREATE TABLE SAL_HISTORY (EmpNo CHAR (6), Salary INTEGER NOT NULL,

Cursor variables as parameters, Cursor Variables As Parameters You can...

Cursor Variables As Parameters You can declare the cursor variables as the formal parameters of the functions and procedures. In the illustration below, you define the REF CUR

Translate the given er schema into sql, Consider the schema for FreeCheckin...

Consider the schema for FreeChecking Bank, that we designed given below. Translate the given ER schema into SQL CREATE TABLE statements (indicating primary key, unique and foreign

Special cases of projection, Special cases of projection This section ...

Special cases of projection This section describes the identity projection, r {ALL BUT}, and the projection on no attributes, r { }, which yields TABLE_DUM when r is empty, ot

Theory of eternity of life - origin of life, THEO R Y OF ETERNITY OF LIFE...

THEO R Y OF ETERNITY OF LIFE (PRAYER - 1880) - The theory of eternity of life, also called the steady-state theory , states that life has ever been in existence as at presen

Using host arrays - bulk bind performance improvement, Using Host Arrays ...

Using Host Arrays The Client-side programs can use anonymous PL/SQL blocks to bulk-bind input and output host arrays. However, this is the well-organized way to pass the colle

3cx pbx sync windows service, 3CX PBX sync Windows Service Project Descr...

3CX PBX sync Windows Service Project Description: !! You require access to a commercial version of the 3CX PBX system in order to be able to program the API !! !! You requ

Iteration schemes- iterative control, Iteration Schemes The bounds of a ...

Iteration Schemes The bounds of a loop range can be variables, literals, variables, or expressions but must compute to integers. Below are some of the examples. As you can see t

Restriction and and - sql, Restriction and AND - SQL Restriction is av...

Restriction and AND - SQL Restriction is available via the WHERE operator, and so it is in SQL. However, by Example showing how a certain simple restriction can be expressed u

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd