Скачать или смотреть Mastering MySQL Row Positioning with ORDER BY

Learn how to accurately get row positions in MySQL datasets using ORDER BY and temporary tables for precise data management.
---
This video is based on the question https://stackoverflow.com/q/74334097/ asked by the user 'Stephen Bouffe' ( https://stackoverflow.com/u/1515092/ ) and on the answer https://stackoverflow.com/a/74334319/ provided by the user 'Stephen Bouffe' ( https://stackoverflow.com/u/1515092/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: MySQL Row Position Using ORDER BY

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Mastering MySQL Row Positioning with ORDER BY

When working with large databases in MySQL, correctly identifying the position of a record can be crucial for data analysis and reporting. This guide addresses a common challenge faced by developers and data analysts alike: How to accurately obtain the position of a specific record when using ORDER BY in your queries.

The Problem: Finding the Row Position

You might encounter a situation where you run a SELECT query to retrieve data, and you realize that although a specific record (say, with cust_number) appears in a certain position when ordered, your method for determining that position returns an unexpected result. For instance, you are aware that the record with cust_number shows up in position 6 when using ORDER BY, but your query returns a position of 37327, which is essentially its non-ordered position.

This discrepancy arises from the way you're calculating the row numbers in conjunction with the ordering criteria. Let's look into how we can resolve this issue effectively.

The Solution: Using a Temporary Table

One effective approach to accurately determining the position of a record based on an ordered dataset is by utilizing a temporary table. This allows you to capture the ordered results in a structured manner and easily retrieve the position you need.

Step-by-Step Implementation

Here’s how you can achieve this in MySQL:

Create a Temporary Table: First, create a temporary table that will store the ordered records along with a unique identifier for each row.

[[See Video to Reveal this Text or Code Snippet]]

Insert Ordered Records: Populate this temporary table with the ordered results from your main dataset. For instance, you can order by company, surname, first_name, and title as below:

[[See Video to Reveal this Text or Code Snippet]]

Fetch the Row Position: Now, with the data organized in the temporary table, retrieve the position of the specific cust_number you are interested in:

[[See Video to Reveal this Text or Code Snippet]]

Clean Up: Finally, after retrieving the position, remember to drop the temporary table to free up resources.

[[See Video to Reveal this Text or Code Snippet]]

Benefits of this Approach

Accurate Positioning: By using a temporary table, you ensure that your row numbers reflect the order of your dataset rather than the default row numbers.

Performance: Temporary tables can be more efficient for this type of operation as they reside in memory and can streamline data retrieval processes.

Simplicity: This method simplifies your SQL logic, making it easier to maintain and understand.

Conclusion

When faced with the challenge of finding the correct position of records in an ordered dataset in MySQL, turning to temporary tables can be a game-changer. By following the outlined steps, you can ensure that your queries yield accurate results, aligning the expected and actual positions of the records. This approach not only enhances your SQL skills but also equips you with a powerful tool for data management in relational databases.

Utilize these techniques in your future data handling tasks, and you'll see how easily you can manipulate and analyze large datasets with precision!