2. Sanooja Jabbar T
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+91-9895519936
Transactions in
MySQL

3. Disclaimer: This presentation is prepared by trainees of
baabtra as a part of mentoring program. This is not official
document of baabtra –Mentoring Partner
Baabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt . Ltd

4. Why Transactions??
• Many applications require a lot of users to access the data
simultaneously
e.g. airline booking systems
• Uncontrolled simultaneous access can result in
inconsistency, so some controlling mechanism is required

5. Transactions
“A transaction is a logical unit of work which takes the DB from
one consistent state to another, i.e. obeying constraints”
• A transaction is a sequential group of one or more SQL
commands.
• Which is performed as one single work unit.
• A transaction will never be complete unless each individual
operation within the group is successful

6. Transactions
• Database transactions are logical units of work which must
ALL be performed to maintain data integrity
• E.g. Move money from one account to another
UPDATE tbl_Account
SET int_balance = int_balance – 100
WHERE int_accountNo = 123;
UPDATE tbl_Account
SET int_balance = int_balance + 100
WHERE int_accountNo = 124;

7. Transactions
• A transaction is the execution of a program that accesses
the DB and
starts with a BEGIN operation,
followed by a sequence of READ and WRITE operations,
ending with a COMMIT operation.
• An update,
for example adding 10 to a value, will actually
Begin
first read the value,
calculate the new value,
and then write the new value commit

8. Transactions
Transactions are used for three purposes in DBMS:
• To determine when integrity constraint checks should
occur (only at the end of transactions)
• To control concurrent access. Gives a single user the
illusion of being the sole user of the database
• To manage recovery from system crashes

9. Properties Of Transactions
• The properties of transactions collectively called ACID
Properties
Atomicity
Consistency
Isolation
Durability

10. Properties Of Transactions
• Atomicity: Ensures that all operations within the work
unit are completed successfully.
• Consistency: Ensures that the database properly changes
states upon a successfully committed transaction.
• Isolation: Data used within a transaction cannot be used
by another transaction until the first transaction is
completed.
• Durability: Ensures that the result or effect of a
committed transaction persists in case of a system failure.

11. Transactions States

12. Transactions States(Contd..)
• Active: In this, the transaction is being executed. This is
the initial state of every transaction.
• Partially Committed: When a transaction executes its
final operation, it is said to be in this state. After
execution of all operations, the database system performs
some checks e.g. the consistency state of database after
applying output of transaction onto the database.
• Failed: If any checks made by database recovery system
fails, the transaction is said to be in failed state, from
where it can no longer proceed further.

13. Transactions States(Contd..)
• Aborted: If any of checks fails and transaction reached
in Failed state, the recovery manager rolls back all its
write operation on the database to make database in the
state where it was prior to start of execution of
transaction. Transactions in this state are called aborted.
Database recovery module can select one of the two
operations after a transaction aborts:
- Re-start the transaction
- Kill the transaction
• Committed: If transaction executes all its operations
successfully it is said to be committed. All its effects are
now permanently made on database system.

14. Transactions States(Contd..)
• The transaction can be control by setting autocommit.
• Set autocommit disables or enables the default
autocommit mode for the current session.
• You can disable the autocommit mode implicitly for a single
series of statements by using the start transaction
statement
set autocommit=0|1

15. Transactions in MySQL
• To successfully transfer money, use the START TRANSACTION and
COMMIT commands:
DECLARE done INT DEFAULT 0;
DECLARE CONTINUE HANDLER FOR SQLWARNING,SQLEXCEPTION SET done=1;
START TRANSACTION;
UPDATE tbl_Account
SET balance = balance – 100
WHERE accountNo = 123;
UPDATE Account
SET balance = balance + 100
WHERE accountNo = 124;
IF done=0 THEN
COMMIT;
ELSE ROLLBACK;
The database is not updated until the COMMIT command is executed

16. Problem 1
• Create table tbl_login and tbl_user ,then create a stored
procedure with transaction to insert the details into both
tables and make sure that entry must be going to both
tables.

17. //Creating table tbl_user
CREATE TABLE tbl_user
( pk_int_profile_id int primary key auto_increment,
vchr_fullname VARCHAR(200),
vchr_address VARCHAR(250),
vchr_mobile_num VARCHAR(15),
dat_dob DATE,
vchr_gender VARCHAR(8));
//Creating table tbl_login
CREATE TABLE tbl_login
( pk_int_login_id int primary key auto_increment,
vchr_login_id VARCHAR(50),
vchr_password VARCHAR(50),
fk_int_user_id int,
FOREIGN KEY (fk_int_user_id) REFERENCES tbl_user(pk_int_user_id));

18. //Stored Procedure with Transaction for inserting the values to tbl_user and tbl_login:
DELIMITER //
CREATE PROCEDURE CSP_INSERT_DETAILS
( IN vchr_login VARCHAR(50), IN vchr_pwd VARCHAR(50),
IN int_user_id int, IN vchr_fname VARCHAR(200),
IN vchr_addr VARCHAR(250), IN vchr_mob_num VARCHAR(15),
IN dat_dob DATE, IN vchr_gen VARCHAR(8))
BEGIN
DECLARE int_last INT;
DECLARE done INT DEFAULT 0;
DECLARE CONTINUE HANDLER FOR SQLWARNING,SQLEXCEPTION SET done=1;
START TRANSACTION;
INSERT INTO tbl_login (vchr_login_id,vchr_password,fk_int_user_id)
VALUES(vchr_login,vchr_pwd,int_user_id);
SET int_last = LAST_INSERT_ID();
INSERT INTO
tbl_user_profile(vchr_fullname,vchr_address,vchr_mobile_num,dat_dob,vchr_gender,fk_int_login
_id) VALUES(vchr_fname,vchr_addr,vchr_mob_num,dat_dob,vchr_gen,int_last);
IF done=0 THEN
COMMIT;
ELSE
ROLLBACK;
END IF;
END //
DELIMITER ;

19. Calling the procedure:
call csp_insert_details("ram","ram123",1,"ram raj","Malaparamba”,"88991222","1989-10-
12","Male");
call csp_insert_details("john","john123",2,"Johnny","Malaparamba","889913322","1988-10-
12","Male");
call csp_insert_details("roy","roy123",2,"roy mathew","Malaparamba","889913344","1988-10-
10","Male");
Then the tables becomes:

20. Any Doubts ??

21. Thanks For
Listening...
The End

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