我正在尝试获得如下输出：
Average score
10
col1 col2 score
...
使用
SELECT AVG(Score), *
FROM (
SUM(...) AS col1
SUM(...) AS col2
SUM(...) AS Score
) AS T1
当我仅选择AVG（Score）或*而不同时选择两者时，此方法有效。有什么办法可以做到而无需重复代码？
这是我尝试时遇到的错误：
ERROR 1064 (42000) at line 27: 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 (
SELECT
testresults.hostname AS Hostname,
hostinfo.env A' at line 3
最佳答案
您不能将*与其他列一起使用。您可以执行以下任一操作：
SELECT * FROM...
要么
SELECT col1, col2, col3... FROM...
但不是
SELECT col1, col2, col3, * FROM...
例：
mysql> SELECT id FROM users LIMIT 5;
+----+
| id |
+----+
| 18 |
| 22 |
| 23 |
| 26 |
| 27 |
+----+
5 rows in set (0.00 sec)
mysql> SELECT id, * FROM users LIMIT 5;
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 users LIMIT 5' at line 1
关于mysql - MySQL如何显示列和表的平均值，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/42771625/