Question

I have one problem that I can’t resolve.

I have 2 tables.

Table 1:

ID | Time
1  | 08:12:54
2  | 08:15:40
3  | 09:30:01
4  | 10:15:15
5  | 10:56:12
6  | 11:00:03

Table 2:

ID | Name| Previous | Current
1  | Queue | null | 11
2  | Queue | 11 | 19
3  | Queue | 19 | 11
3  | List | null | 11
4  | Queue | 11 | 16
4  | List | null | 11
5  | Queue | null | 15
6  | Queue | 15 | 19

The result wanted:

NumberQueue | Start | End
11 | 08:12:54 | 08:15:40
19 | 08:15:40 | 09:30:01
11 | 09:30:01 | 10:15:15
15 | 10:56:12 | 11:00:03
...
...

The previous and the current fields, have the number of the Queue and I want to know for each Queue, the start date and the end date, knowing that the previous has the previous Queue, and the current has the new Queue.

I want one query that can present this result. Help me. 🙁

Regards.

Answer 1

This select statement should provide the information you need:

SELECT Current AS Number, t1out.Time AS Start, (
    SELECT Time FROM Table1 AS t1in
    WHERE t1in.ID > t1out.ID
    ORDER BY ID ASC LIMIT 1
) AS End FROM Table2
LEFT JOIN Table1 AS t1out USING (ID)
WHERE Table2.Name = 'Queue';