SQL transactions are essential for maintaining database integrity as they allow for grouping multiple SQL statements into a single unit that can be committed or rolled back. Key properties of transactions include atomicity, consistency, isolation, and durability, ensuring that operations are reliable and accurate even during failures. The proper use of commit and rollback commands in transactions aids in error handling and protecting against data integrity issues.

1. DATABASE TRANSACTION
YOURNAME

2. CONTENT
• Idea Of Transaction
• Why Are Sql Transactions Necessary & When Should You Use?
• Properties Of Transaction
• What Is Commit And Rollback
• Difference Between Commit And Rollback In Sql
• Syntax & implementation

3. - Idea of transaction.
A SQL transaction is a grouping of one or more SQL statements that
interact with a database. A transaction in its entirety can commit to a
database as a single logical unit or rollback (become undone) as a single
logical unit. In SQL, transactions are essential for maintaining database
integrity. They are used to preserve integrity when multiple related
operations are executed concurrently, or when multiple users interact with a
database concurrently.

5. - Why are SQL Transactions Necessary & when should you use?
A database application has to account for every possible failure scenario while writing and reading
from a database. Without SQL transactions, application code that protects database integrity
would be complex and expensive to develop and maintain. With SQL transactions, application
code and database maintenance can be simplified.

6. - Properties of Transaction
 Atomicity: The outcome of a transaction can either be completely
successful or completely unsuccessful. The whole transaction must be rolled
back if one part of it fails.
 Consistency: Transactions maintain integrity restrictions by moving the
database from one valid state to another.
 Isolation: Concurrent transactions are isolated from one another,
assuring the accuracy of the data.
 Durability: Once a transaction is committed, its modifications remain in
effect even in the event of a system failure.

7. - what is commit and rollback
A COMMIT means that the changes made in the current transaction are made
permanent and become visible to other sessions. A ROLLBACK statement, on
the other hand, cancels all modifications made by the current transaction.
Both COMMIT and ROLLBACK release all InnoDB locks that were set during
the current transaction.

8. Difference between COMMIT and ROLLBACK in SQL
1. COMMIT
COMMIT in SQL is a transaction control language that is used to permanently save the changes done in the
transaction in tables/databases. The database cannot regain its previous state after its execution of COMMIT
.
2. ROLLBACK
ROLLBACK in SQL is a transactional control language that is used to undo the transactions that have not
been saved in the database. The command is only been used to undo changes since the last COMMIT.

9. Syntax & implementation
SQL Server
BEGIN TRANSACTION NameOfTransaction;
ROLLBACK;
COMMIT TRANSACTION;
MYSQL
START TRANSACTION;

10. To demonstrate the mechanism behind transaction processing, consider
the example of a simple database named School. One of the tables in
the database is named Course and is defined as follows:
COURSE
CourseId
CourseName
The Course table is created using the below SQL
command:
CREATE TABLE Course(
CourseId SMALLINT NOT NULL;
CourseName VARCHAR(40) NOT NULL
);

11. Example 1: Commit a Transaction (SQL)
The example below obtains the largest CourseId value from table Course and adds 1 to it.
It then inserts a row into the Course table and commits the transaction. Before committing,
if any part of the CourseAdd transaction fails to execute, then none of the transactions can be processed.
That means if the Select or Insert statement fails in some capacity,
the entire transaction is null and void.
BEGIN TRANSACTION CourseAdd;
DECLARE @CrsId SMALLINT;
SELECT @CrsId = MAX(CourseId) + 1
FROM Course;
INSERT Course VALUES (@CrsId, 'Biology 101');
COMMIT TRANSACTION;

12. Example 2: Roll Back a Transaction (MYSQL)
In the example below, although rows are manually inserted into the Course table,
all the Insert statements are wrapped into a transaction. That way, if a transaction fails to execute,
you can roll back the entire transaction using the following MySQL syntax:
START TRANSACTION;
INSERT Course VALUES (1, 'Biology 101');
INSERT Course VALUES (2, 'Computer Science 101');
ROLLBACK;

13. Example 3: Combining Commit and Rollback in a Transaction
The example below combines the ability to both commit and rollback
transactions in the same transaction code block.

14. BEGIN TRANSACTION InsertCourse;
DECLARE @CrsId SMALLINT;
SELECT @CrsId = MAX(CourseId) + 1
FROM Course;
INSERT Course VALUES (@CrsId, 'Biology 101');
IF (SELECT COUNT(CourseName)
FROM Course
WHERE CourseName = 'Biology 101') > 1
ROLLBACK;
END IF;
COMMIT TRANSACTION;

15. More Benefits of Using Transactions
When should you use transactions? Should you always use transactions?
The simple answer is yes. This is especially true when you are dealing with multiple groups of
statements. In a transaction, all of the statements in a sequence of statements must succeed for the
associated data to be committed to the database. A failure of a component within the transaction
necessitates a rollback.
The use of transactions is also beneficial to protect against database failure conditions, including
power failures, server crashes, disk drive failure, and database software crashes. In the event of one
of these failures, if there are transactions that have not yet been committed, database integrity is
maintained. Without transactions, any atomic statements that are applied to the database remain
intact, regardless of whether associated statements have been executed. This may result in a data
integrity issue.

16. Conclusion
SQL transaction logic is a fundamental mechanism for ensuring database integrity
and minimizing error handling logic that is required in a multi-user database
application. The use of transactions in SQL environments guarantees accuracy and
completeness.