How Can I Retrieve the Current Transaction Isolation Level in SQL Server?

Understanding and Retrieving Your SQL Server Transaction Isolation Level

Knowing the current transaction isolation level in your SQL Server database is vital for maintaining data consistency and predicting database behavior. This guide provides a simple method to retrieve this crucial information.

The Query

Execute the following SQL query to determine your database's current transaction isolation level:

<code class="language-sql">SELECT CASE transaction_isolation_level
    WHEN 0 THEN 'Unspecified'
    WHEN 1 THEN 'ReadUncommitted'
    WHEN 2 THEN 'ReadCommitted'
    WHEN 3 THEN 'Repeatable'
    WHEN 4 THEN 'Serializable'
    WHEN 5 THEN 'Snapshot'
END AS TRANSACTION_ISOLATION_LEVEL
FROM sys.dm_exec_sessions
WHERE session_id = @@SPID;</code>

Query Breakdown:

• transaction_isolation_level: This column contains the numerical code representing the isolation level.
• CASE statement: This translates the numerical code into its corresponding descriptive name.
• sys.dm_exec_sessions: This dynamic management view provides details about active SQL Server sessions.
• @@SPID: This system variable returns the ID of the current session.

Understanding the Results

The query will return one of the following transaction isolation levels:

• Unspecified (0)
• Read Uncommitted (1)
• Read Committed (2)
• Repeatable Read (3)
• Serializable (4)
• Snapshot (5)

For a comprehensive understanding of each isolation level's characteristics and best-use cases, consult the official Microsoft SQL Server documentation.

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