如何在SQL中透视该表

Question

I came across this issue when trying to make use of this "active users" table from Microsoft NAV. What I got asked to do is a Dashboard in Power BI or other tool that will allow the company I work for to understand how many users are active on the NAV system at any point in time. I found a DAX formula in Power BI that could do the trick - but it requires the following table transformation:

I am trying to do this in SQL Management Studio:

My SQL Server is Microsoft SQL Azure (RTM) - 12.

How could I pivot this NAV table below with the following structure knowing that Session ID might repeat further down the line?

Session ID  |    Event Datetime       | Event Type
350              2017-07-01 01:00       Logon
350              2017-08-01 02:00       Logoff
351              2017-07-01 02:00       Logon
351              2017-08-01 03:00       Logoff
350              2017-09-01 01:00       Logon
350              2017-09-01 02:00       Logoff

The final result would be each Session ID against their Logon and Logoff time (allowing duplicates if Session ID repeats like in this example)

Thanks a lot in advance.

Best

Andre

Answer 1

This is TSQL code and will run on an Azure database. I think this will get you the results you are looking for.

DECLARE @ActiveUsersLog AS TABLE
      (
          sessionId     INT
         ,EventDateTime DATETIME
         ,EventType     VARCHAR(50)
      );

INSERT INTO @ActiveUsersLog
     (
         sessionId
        ,EventDateTime
        ,EventType
     )
VALUES
     (350, '2017-07-01 01:00', 'Logon')
    ,(350, '2017-08-01 02:00', 'Logoff')
    ,(351, '2017-07-01 02:00', 'Logon')
    ,(351, '2017-08-01 03:00', 'Logoff')
    ,(350, '2017-09-01 01:00', 'Logon')
    ,(350, '2017-09-01 02:00', 'Logoff');

WITH cte_logon
    AS (
           SELECT aul.sessionId
                 ,aul.EventDateTime
                 ,seq = RANK() OVER (PARTITION BY aul.sessionId ORDER BY aul.EventDateTime)
             FROM @ActiveUsersLog AS aul
            WHERE aul.EventType = 'Logon'
       )
    ,cte_logoff
    AS (
           SELECT aul.sessionId
                 ,aul.EventDateTime
                 ,seq = RANK() OVER (PARTITION BY aul.sessionId ORDER BY aul.EventDateTime)
             FROM @ActiveUsersLog AS aul
            WHERE aul.EventType = 'Logoff'
       )
SELECT o.sessionId
      ,LogonTime = o.EventDateTime
      ,LogoffTime = f.EventDateTime
  FROM cte_logon AS o
      LEFT OUTER JOIN cte_logoff AS f
          ON o.sessionId = f.sessionId
             AND o.seq = f.seq;

If you are only looking for active users then you would add this where clause: (make sure to remove the semicolon at the end of the code above before adding a where clause)

where f.EventDateTime is null

Answer 2

Without knowing the flavour of SQL, I can only give you basic advice.

By performing an inner join with both sides lining to the same table (aliasing appropriately) matching on the session_id of both sides, you can then filter Event Type on one of the aliased tables to equal Logon and Event Type on the other aliased table to match Logoff .

This method should work on just about any form of SQL I've used, as it's core functionality of SQL.