SELECT DISTINCT *错误的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 

任何人都可以让知道的上述查询正确的语法？

Answer 1

对于DISTINCT您需要提供一个可供使用的列DISTINCT。

因此，举例来说，你的情况：SELECT DISTINCT(a) FROM abc

您希望计算表中的行，基于一个独特的价值？

SELECT COUNT (DISTINCT a) FROM abc 

没有必要为GROUP BY作为DISTINCT已经采取的照顾。