sql -两列的计数

Question

我在一个数据库中放了很多行，我有这个：

+----+---------------------+-------------+----------------+-----------+
| ID | time                | os_name     | program        | last_line |
+----+---------------------+-------------+----------------+-----------+
| 14 | 2019-01-04 14:00:00 | titi        | roro           | 109       |
| 15 | 2019-01-04 14:00:00 | titi        | roro           | 109       |
| 16 | 2019-01-04 14:00:00 | gege        | fefe           | 109       | 

我想要：

+---------------------+-------------------------+-------------+-----------+-----------+
| time                | nb_os_name_program      | os_name     | program   | last_line |
+---------------------+-------------------------+-------------+-----------+-----------+
| 2019-01-04 14:00:00 |                      2  | titi        | roro      | 109       |
| 2019-01-04 14:00:00 |                      1  | gege        | fefe      | 109       | 

Answer 1

具有聚合功能的简单GROUP BY将帮助您：

SELECT time, os_name, count(*) as nb_os_name, program, lastline, 
FROM table t
GROUP BY time, os_name, program, lastline