Get Latest Record In Each MySQL Group | How to select the first/least/max row per group in SQL | Select max, min, last row for each group in SQL without a subquery | MySQL - How To Get Top N Rows per Each Group

First approach (LEFT JOIN)

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SELECT s.Name,c1.Id AS Max_Score_ID,c1.Score as Max_Score
FROM Students s
LEFT JOIN Scores c1 ON (c1.Student=s.Id)
LEFT JOIN Scores c2 ON (
  c1.Student=c2.Student 
  AND (c1.Score<c2.Score OR (c1.Score=c2.Score AND c1.Id<c2.Id))
)
WHERE c2.Score IS NULL
ORDER BY c1.Score DESC;

Execution Plan: First image shows statistics, an index is used when performing the above SQL, example created in MySQL-Fiddle. And second image for large data size, its around 8 million rows, and it takes a small amount of time to execute.

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Now we will go for second approach (GROUP_CONCAT WITH SUBSTRING_INDEX)

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SELECT s.Name,
CAST(SUBSTRING_INDEX(
  GROUP_CONCAT(c1.Id order by c1.Score desc),',',1
) AS DECIMAL(10, 2)) AS Max_Score_ID,
CAST(SUBSTRING_INDEX(
  GROUP_CONCAT(c1.Score order by c1.Score desc),',',1
) AS DECIMAL(10, 2)) as Max_Score
FROM Students s
LEFT JOIN Scores c1 ON (c1.Student=s.Id)
GROUP BY s.Id
ORDER BY Max_Score DESC;

Execution plan: First image show statistics taken from MySQL-Fiddle, used group-concat and substring-index both to calculate (min/max) value and/or other column of the table. Second image show that its also good time effective as it also takes a small amount of time to get min/max value and table size around 8 million rows.

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MySQL Fiddle Link

Get Latest Record In Each MySQL Group

Table=check_group_by
id   group_by    value
-------------------------
1    1           Value 1
2    1           Value 2
3    1           Value 3
4    2           Value 4
5    2           Value 5
6    3           Value 6

Query will be as like:

SELECT id,group_by,value FROM check_group_by
WHERE id IN (
 SELECT MAX(id) FROM check_group_by GROUP BY group_by
)

SQL Fiddle Example