MySQL：测试与查询的连接？

SELECT yourValue;

SELECT anyPredefinedFunctionName();

Mysql> select "This is mysql" as Display;

+---------------+
| Display       |
+---------------+
| This is Mysql |
+---------------+
1 row in set (0.00 sec)

mysql> select 10*3 as MultiplicationResult;

+---------------------+
| MultiplicationResult|
+---------------------+
| 30                  |
+---------------------+
c1 row in set (0.00 sec)

mysql> select connection_id() as ConnectionId;

+--------------+
| ConnectionId |
+--------------+
| 8            |
+--------------+
1 row in set (0.00 sec)

mysql> select database();

+------------+
| database() |
+------------+
| sample     |
+------------+
1 row in set (0.00 sec)