Isolation levels in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the transaction isolation level to READ COMMITTED.

MySQL

SET TRANSACTION ISOLATION LEVEL [1];

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AREAD COMMITTED

BREPEATABLE READ

CREAD UNCOMMITTED

DSERIALIZABLE

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing READ UNCOMMITTED which allows dirty reads.

Using SERIALIZABLE which is stricter than needed.

The READ COMMITTED isolation level ensures that any data read is committed at the moment it is read. This prevents dirty reads.

2fill in blank

medium

Complete the code to start a transaction with the SERIALIZABLE isolation level.

MySQL

START TRANSACTION ISOLATION LEVEL [1];

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AREAD UNCOMMITTED

BREAD COMMITTED

CSERIALIZABLE

DREPEATABLE READ

Attempts:

3 left

💡 Hint

Common Mistakes

Using REPEATABLE READ which is less strict.

Forgetting to specify the isolation level in the transaction start.

SERIALIZABLE is the strictest isolation level, preventing phantom reads and ensuring full transaction isolation.

3fill in blank

hard

Fix the error in the code to set the isolation level globally.

MySQL

SET GLOBAL TRANSACTION ISOLATION LEVEL [1];

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AREPEATABLE READ

BREAD UNCOMMITTED

CREAD COMMITTED

DSERIALIZABLE

Attempts:

3 left

💡 Hint

Common Mistakes

Using an unsupported isolation level for global setting.

Syntax errors in the SET GLOBAL command.

The default global isolation level in MySQL is REPEATABLE READ. This command sets it correctly.

4fill in blank

hard

Fill both blanks to complete the query that shows the current transaction isolation level.

MySQL

SELECT @@transaction_isolation AS [1], @@global.transaction_isolation AS [2];

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Acurrent_level

Bglobal_level

Cisolation_level

Dlevel

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same alias for both columns.

Using non-descriptive alias names.

The query returns the current session isolation level as 'isolation_level' and the global isolation level as 'global_level'.

5fill in blank

hard

Fill the blanks to complete the code that sets the isolation level for the next transaction and then starts it.

MySQL

SET SESSION TRANSACTION ISOLATION LEVEL [1]; START TRANSACTION [2];

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AREAD COMMITTED

BISOLATION LEVEL SERIALIZABLE

CREAD UNCOMMITTED

DISOLATION LEVEL READ COMMITTED

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing isolation level keywords incorrectly.

Not specifying isolation level in START TRANSACTION.

The first statement sets the session isolation level to READ COMMITTED. The second starts a transaction with SERIALIZABLE isolation level specified explicitly.