如何做嵌套的选择

Question

I would like to see the result of code_2 into result ofcode_1 using nested SELECT. Can you help me to do this? I use database - Oracle PL/SQL Developer Thanks a lot in advance

code_1:

SELECT DISTINCT eventattribute1
FROM   table1 partition(m201302) 
WHERE  eventattribute22 = 'EURO' 
       AND eventattribute13 = 'MC_PO_ROAM' 
       AND eventattribute14 != 'T' 
       AND event_cost != '0' 
GROUP  BY eventattribute1 

code_2:

SELECT Numtodsinterval(Sum(To_char(To_date(duration, 'HH24:MI:SS'), 
                           'HH24') * 
                                  3600 + 
                                                      To_char( 
                                  To_date(duration, 'HH24:MI:SS'), 
                                                      'MI') 
                                                      * 60 + 
                                  To_char(To_date(duration, 
                                          'HH24:MI:SS'), 'SS')), 'second') AS 
       SUMTOTAL 
FROM   table1 partition(m201302) 

Answer 1

To do this as a nested select, you can just add the second query onto the select line of the first. It returns one value and one row, so that is fine. Conceptually, this is:

SELECT eventattribute1,
       <code2>
FROM   table1 partition(m201302) 
WHERE  eventattribute22 = 'EURO' 
       AND eventattribute13 = 'MC_PO_ROAM' 
       AND eventattribute14 != 'T' 
       AND event_cost != '0' 
GROUP  BY eventattribute1 

(The distinct is unnecessary.)

In practice, this looks a bit worse:

SELECT eventattribute1,
       (SELECT Numtodsinterval(Sum(To_char(To_date(duration, 'HH24:MI:SS'), 
                       'HH24') * 
                              3600 + 
                                                  To_char( 
                              To_date(duration, 'HH24:MI:SS'), 
                                                  'MI') 
                                                  * 60 + 
                              To_char(To_date(duration, 
                                      'HH24:MI:SS'), 'SS')), 'second') AS SUMTOTAL 
        FROM   table1 partition(m201302)
       ) as SUMTOTAL
FROM   table1 partition(m201302) 
WHERE  eventattribute22 = 'EURO' 
       AND eventattribute13 = 'MC_PO_ROAM' 
       AND eventattribute14 != 'T' 
       AND event_cost != '0' 
GROUP  BY eventattribute1 

An alternative is to use an analytic function, because you don't need a nested select for this query.

In response to your comment, one method is a correlated subquery:

SELECT eventattribute1,
       (SELECT Numtodsinterval(Sum(To_char(To_date(duration, 'HH24:MI:SS'), 
                       'HH24') * 
                              3600 + 
                                                  To_char( 
                              To_date(duration, 'HH24:MI:SS'), 
                                                  'MI') 
                                                  * 60 + 
                              To_char(To_date(duration, 
                                      'HH24:MI:SS'), 'SS')), 'second') AS SUMTOTAL 
        FROM   table1 partition(m201302) t1
        where t1.eventattribute1 = table1.eventattribute1
       ) as SUMTOTAL
FROM   table1 partition(m201302) 
WHERE  eventattribute22 = 'EURO' 
       AND eventattribute13 = 'MC_PO_ROAM' 
       AND eventattribute14 != 'T' 
       AND event_cost != '0' 
GROUP  BY eventattribute1;

The easier way might be to move it directly into the aggregation . . but you might need to play with the conditions in the where clause;

SELECT eventattribute1,
       Numtodsinterval(Sum(To_char(To_date(duration, 'HH24:MI:SS'), 
                       'HH24') * 
                              3600 + 
                                                  To_char( 
                              To_date(duration, 'HH24:MI:SS'), 
                                                  'MI') 
                                                  * 60 + 
                              To_char(To_date(duration, 
                                      'HH24:MI:SS'), 'SS')), 'second') AS SUMTOTAL 
FROM   table1 partition(m201302) 
WHERE  eventattribute22 = 'EURO' 
       AND eventattribute13 = 'MC_PO_ROAM' 
       AND eventattribute14 != 'T' 
       AND event_cost != '0' 
GROUP  BY eventattribute1