MySQL查詢得到相應的數據重複記錄

Question

這是一個表名test1的

id Roll Rank Grade 
1 10 50 A 
2 20 60 B 
3 30 40 X 
4 20 50 A 
5 30 90 O 
6 10 80 C 

想造成以下格式：

id Roll Rank Grade 
1 10 50,80  A,C 
2 20 60,80  B,A 
3 30 40,90  X,O 

Answer 1

這將這樣的伎倆：

SELECT id, Roll, GROUP_CONCAT(Rank), GROUP_CONCAT(Grade) 
FROM your_table 
GROUP BY Roll 
HAVING COUNT(*) > 1 

Answer 2

試試這個：

SELECT A.id, A.Roll, 
     GROUP_CONCAT(A.Rank ORDER BY A.id) AS Rank, 
     GROUP_CONCAT(A.Grade ORDER BY A.id) AS Grade 
FROM test1 A 
GROUP BY A.Roll 
ORDER BY A.Roll;