How to Efficiently Retrieve Rows with the Lowest Value for Each Dealer in MySQL?

Retrieve Rows with Lowest Value for Multiple Dealers Using MySQL

In a database with columns including id, name, value, and dealer, you aim to retrieve rows with the lowest value for each distinct dealer. While attempting with MIN() and GROUP BY, you haven't found a solution.

Recommended Solutions:

Solution 1:

SELECT t1.* FROM your_table t1
JOIN (
  SELECT MIN(value) AS min_value, dealer
  FROM your_table 
  GROUP BY dealer
) AS t2 ON t1.dealer = t2.dealer AND t1.value = t2.min_value

Solution 2 (Faster):

SELECT t1.* FROM your_table t1
LEFT JOIN your_table t2
ON t1.dealer = t2.dealer AND t1.value > t2.value
WHERE t2.value IS NULL

Explanation:

Solution 1 utilizes a subquery to find the minimum value for each dealer. It then joins this subquery with the main table to retrieve the corresponding rows.

Solution 2 leverages a self-join to efficiently find rows with the lowest value for each dealer. It uses a LEFT JOIN, checking if there's a row with a lower value. If not, it's the lowest value for that dealer.

Additional Information:

This is a commonly encountered MySQL issue. Refer to the documentation here: "Rows Holding the Group-wise Maximum/Minimum of a Certain Column" for more details.

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