Setting MySQL Isolation Level to READ COMMITTED

Set Isolation Level to Read Committed

Write a MySQL query to set the isolation level to READ COMMITTED and perform a read operation.

Solution:

-- Set the transaction isolation level to READ COMMITTED:
-- This ensures that only committed data is read, preventing dirty reads.
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;

-- Begin a new transaction
START TRANSACTION;

-- Select all employees from DepartmentID = 2:
-- This query retrieves the latest committed data at the time of execution.
SELECT * FROM Employees WHERE DepartmentID = 2;

-- Commit the transaction:
-- Since there are no data modifications (only a SELECT statement), this step is not strictly necessary,
-- but it ensures the transaction is properly closed.
COMMIT; 

Explanation:

• Purpose of the Query:
• The goal is to ensure that only committed data is read during the transaction.
• This demonstrates the use of isolation levels.
• Key Components:
• SET TRANSACTION ISOLATION LEVEL READ COMMITTED: Sets the isolation level.
• SELECT * FROM Employees: Reads data from the Employees table.
• Why use Transactions?:
• Isolation levels control the visibility of changes made by other transactions, ensuring data consistency.
• Real-World Application:
• For example, in a banking system, you might use READ COMMITTED to ensure that only finalized transactions are visible.

For more Practice: Solve these Related Problems:

• Write a MySQL query to set the isolation level to READ COMMITTED and perform an update operation.
• Write a MySQL query to demonstrate how READ COMMITTED prevents dirty reads in a concurrent environment.
• Write a MySQL query to set the isolation level to READ COMMITTED and execute multiple SELECT queries to check for consistency.
• Write a MySQL query to compare the behavior of READ COMMITTED with READ UNCOMMITTED using concurrent transactions.

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Previous MySQL Exercise: Rollback a Transaction on Error.
Next MySQL Exercise: Set Isolation Level to Serializable.