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Thread: SQL Query Optimization: Combining Multiple Joins for Improved Performance

  1. #1
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    SQL Query Optimization: Combining Multiple Joins for Improved Performance

    I'm working on an SQL query for a complex reporting system that involves multiple tables and joins. However, the query's performance is not meeting my expectations, and I suspect that the way I've structured my joins might be inefficient.


    Here's a simplified version of my query:

    SELECT
        orders.order_id,
        customers.customer_name,
        products.product_name,
        order_details.quantity,
        order_details.unit_price
    FROM
        orders
    JOIN
        customers ON orders.customer_id = customers.customer_id
    JOIN
        order_details ON orders.order_id = order_details.order_id
    JOIN
        products ON order_details.product_id = products.product_id
    WHERE
        orders.order_date BETWEEN '2023-01-01' AND '2023-12-31';
    While this query returns the correct results, it's taking a significant amount of time to execute, especially when dealing with a large dataset.


    I'd like to optimize this query for better performance. Could someone review my SQL code and suggest improvements or alternative approaches to achieve the same result more efficiently? Additionally, are there any indexing strategies or database design considerations that might help enhance the query's speed? Any insights or code optimizations would be greatly appreciated. Thank you!

  2. #2
    Moderator VBAX Guru Aussiebear's Avatar
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    Have a look here to see if this can improve your code. https://blog.devart.com/how-to-optimize-sql-query.html. In particular look at the section where it recommends keeping the number of joins to a minimum by using Inner Join
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  3. #3
    you should also try to create index on the Join fields and on the Criteria field.

  4. #4
    Quote Originally Posted by arnelgp View Post
    you should also try to create index on the Join fields and on the Criteria field.connections
    How to create index on Join field and on Criteria field?

  5. #5
    Moderator VBAX Guru Aussiebear's Avatar
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    Remember To Do the Following....
    Use [Code].... [/Code] tags when posting code to the thread.
    Mark your thread as Solved if satisfied by using the Thread Tools options.
    If posting the same issue to another forum please show the link

  6. #6
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    Quote Originally Posted by arnelgp View Post
    you should also try to create index on the Join fields and on the Criteria field. immaculate grid
    Thanks for sharing your expertise on indexing. Creating an index on the Join fields and on the Criteria field is a good suggestion to improve query performance.

  7. #7
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    You can use this tool to see exactly where SQL Server uses the most time running the query Analyze an Actual Execution Plan - SQL Server | Microsoft Learn

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