How to Find the Row with the Lowest Value for Each Dealer in MySQL?

Obtaining the Lowest Value for Each Dealer in MySQL

Consider a database with the following structure:

CREATE TABLE your_table (
  id INT NOT NULL,
  name VARCHAR(255) NOT NULL,
  value INT NOT NULL,
  dealer VARCHAR(255) NOT NULL
);

Objective: Retrieve the row with the lowest value for each unique dealer.

Solution:

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 (Recommended):

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;

Discussion:

Solution 1 employs a subquery to find the minimum value for each dealer and then joins that information with the original table to collect the complete row data. Solution 2, on the other hand, uses an optimized left join to eliminate any rows with larger values for the same dealer, effectively returning only those with the lowest values.

MySQL provides a dedicated section in its documentation for this frequently encountered scenario, titled "Rows Holding the Group-wise Maximum/Minimum of a Certain Column." Refer to this documentation for further details and examples.

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