How to Efficiently Find Max/Min Values per Group Using SQL Joins?

Retrieving Maximum/Minimum Values Per Group Using Joins

In this solution, we use a join operation to retrieve rows with the highest or lowest values for a specified column within each group, without resorting to ranking or subqueries.

To find the row with the highest OrderField value per group:

SELECT t1.*
FROM `Table` AS t1
LEFT OUTER JOIN `Table` AS t2
  ON t1.GroupId = t2.GroupId AND t1.OrderField < t2.OrderField
WHERE t2.GroupId IS NULL
ORDER BY t1.OrderField;

In the event of multiple records sharing the same maximum OrderField value within a group, you may want to further refine the condition:

SELECT t1.*
FROM `Table` AS t1
LEFT OUTER JOIN `Table` AS t2
  ON t1.GroupId = t2.GroupId 
        AND (t1.OrderField < t2.OrderField 
         OR (t1.OrderField = t2.OrderField AND t1.Id < t2.Id))
WHERE t2.GroupId IS NULL

This approach ensures that the row with the greatest OrderField value is returned when there are ties within a group.

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