MySQL查询中添加注释有哪几种方式？

# Comment

这个是单行注释。这种注释以 # 字符开始，直到行尾。

-– 注释

 这也是单行注释。后面必须跟空格或控制字符。

/* Comment */

这是多行注释。此语法使注释可以扩展到多行，因为开始和结束序列不必位于同一行。

考虑以下示例来演示所有三种类型的注释 -

mysql> Select NOW() #Single line comment continues to the end of line
    -> ;
+---------------------+
| NOW()               |
+---------------------+
| 2017-11-07 15:04:03 |
+---------------------+
1 row in set (0.00 sec)

mysql> Select NOW() -- Single line comment continues to the end of line
    -> ;
+---------------------+
| NOW()               |
+---------------------+
| 2017-11-07 15:04:17 |
+---------------------+
1 row in set (0.00 sec)

mysql> Select 1 /* in-line comment */ +1;
+-------+
| 1 +1  |
+-------+
|     2 |
+-------+
1 row in set (0.10 sec)

mysql> Select 1 /* in-line comment */ +1;
+-------+
| 1 +1  |
+-------+
|     2 |
+-------+
1 row in set (0.00 sec)

mysql> Select 1
    -> /*
   /*> this is a Multiple-line
   /*> comment
   /*> */
    -> +1;
+-------+
| 1  +1 |
+-------+
|     2 |
+-------+
1 row in set (0.00 sec)

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