SELECT DISTINCT *錯誤的MySQL

Question

我有以下表

mysql> select * from abc; 
+---+------+------+ 
| A | B | C | 
+---+------+------+ 
| 2 | 2 | 2 | 
| 1 | 2 | 3 | 
| 3 | 3 | 2 | 
| 4 | 3 | 3 | 
+---+------+------+ 
4 rows in set (0.00 sec) 



mysql> select count(distinct *) 
    -> from abc 
    -> group by a; 
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that 
corresponds to your MySQL server version for the right syntax to use near '*) 
from abc 
group by a' at line 1 

任何人都可以讓知道的上述查詢正確的語法？

Answer 1

對於DISTINCT您需要提供一個可供使用的列DISTINCT。

因此，舉例來說，你的情況：SELECT DISTINCT(a) FROM abc

您希望計算表中的行，基於一個獨特的價值？

SELECT COUNT (DISTINCT a) FROM abc 

沒有必要爲GROUP BY作爲DISTINCT已經採取的照顧。