How to Identify Rows with No Changes in a Temporal Table

Identifying Rows with No Changes Over Time

Write a SQL query to identify rows that have not changed over time in a temporal table.

Solution:

-- Identify rows with no changes over time.
WITH RowChanges AS (
    SELECT EmployeeID, COUNT(*) AS ChangeCount
    FROM Employees
    FOR SYSTEM_TIME ALL
    GROUP BY EmployeeID
)
SELECT e.EmployeeID, e.Name, e.Position
FROM Employees e
JOIN RowChanges rc ON e.EmployeeID = rc.EmployeeID
WHERE rc.ChangeCount = 1;

Explanation:

• Purpose of the Query :
• The goal is to demonstrate how to identify rows that have not changed over time in a temporal table.
• Key Components :
• FOR SYSTEM_TIME ALL: Retrieves all versions of rows.
• COUNT(*): Counts the number of versions for each row.
• Filters rows where ChangeCount = 1, indicating no changes.
• Why Identify Unchanged Rows? :
• Identifying unchanged rows helps determine which records are stable or static.
• It supports optimization efforts by focusing on frequently changing data.
• Real-World Application :
• In inventory systems, identifying unchanged rows tracks items with consistent stock levels.

Additional Notes:

• Use this query to optimize storage or reporting by excluding static data.
• Combine with additional filters to refine results.
• Important Considerations:
• Ensure that the query accounts for all versions of rows.

For more Practice: Solve these Related Problems:

• Write a SQL query to identify rows that have not changed over time in a temporal table named "Employees".
• Write a SQL query to find records that remained static in a temporal table named "Inventory".
• Write a SQL query to detect rows with no modifications in a temporal table named "Accounts".
• Write a SQL query to locate records that have not been updated since their creation in a temporal table named "Assets".

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Previous SQL Exercise: Querying the Duration of Each Row's Validity.
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