How to make case in HANA

Question

I have the following query in postgres which gives the meter range and the number of vehicles travelled between the range

SELECT (CASE WHEN meter >= 0 AND meter< 10000 THEN '0-10' 
             WHEN meter >= 10000 AND meter < 20000  THEN '10-20' 
             WHEN meter >= 20000 AND meter <30000 THEN '20-30' 
             WHEN meter >= 30000 AND meter < 40000 THEN '30-40' 
             WHEN meter >= 40000 AND meter < 50000 THEN '40-50' 
             WHEN meter >= 50000 AND meter < 60000  THEN '50-60' 
             WHEN meter >= 60000 AND meter <70000 THEN '60-70' 
             WHEN meter >= 70000 AND meter < 80000 THEN '70-80' 
             WHEN meter >= 80000 AND meter < 100000 THEN '80-90' 
             WHEN meter >=100000 THEN 'above 100'  
       END) as range,count(*) as vehicle_count 
        from ( 



      SELECT extract (day from time) as day, place,vehicle_id,sum(meter_two_points) as meter 
FROM public.datatable where time >= '2015-09-05 00:00:00' and time <= '2015-09-05 23:00:00' and place=10 
  group by day,vehicle_id,place 
  order by day,vehicle_id  



)  as A group by range  order by range limit 10

I now want to do the same query for the same table in HANA.So I tried with

 SELECT (CASE   WHEN meter >= 0 AND meter< 10000 THEN '0-10' 
                WHEN meter >= 10000 AND meter < 20000  THEN '10-20' 
                WHEN meter >= 20000 AND meter <30000 THEN '20-30' 
                WHEN meter >= 30000 AND meter < 40000 THEN '30-40' 
                WHEN meter >= 40000 AND meter < 50000 THEN '40-50' 
                WHEN meter >= 50000 AND meter < 60000  THEN '50-60' 
                WHEN meter >= 60000 AND meter <70000 THEN '60-70' 
                WHEN meter >= 70000 AND meter < 80000 THEN '70-80' 
                WHEN meter >= 80000 AND meter < 100000 THEN '80-90' 
                WHEN meter >=100000 THEN 'above 100'  
           END) as range,count(*) as vehicle_count 
            from ( 


            But it throws with the error `invalid column name range`
          SELECT to_integer(to_varchar(time,'DD')) as day, place,vehicle_id,sum(meter_two_points) as meter 
    FROM public.datatable where time >= '2015-09-05 00:00:00' and time <= '2015-09-05 23:00:00' and place=10 
      group by day,vehicle_id,place 
      order by day,vehicle_id  



    )  as A group by range  order by range limit 10

Answer 1

You may change to this:

SELECT range, 
    COUNT(*) AS vehicle_count 
FROM (
    SELECT (CASE   WHEN meter >= 0 AND meter< 10000 THEN '0-10' 
                WHEN meter >= 10000 AND meter < 20000  THEN '10-20' 
                WHEN meter >= 20000 AND meter <30000 THEN '20-30' 
                WHEN meter >= 30000 AND meter < 40000 THEN '30-40' 
                WHEN meter >= 40000 AND meter < 50000 THEN '40-50' 
                WHEN meter >= 50000 AND meter < 60000  THEN '50-60' 
                WHEN meter >= 60000 AND meter <70000 THEN '60-70' 
                WHEN meter >= 70000 AND meter < 80000 THEN '70-80' 
                WHEN meter >= 80000 AND meter < 100000 THEN '80-90' 
                WHEN meter >=100000 THEN 'above 100'  
           END) AS range
    FROM ( 
        SELECT to_integer(to_varchar(time,'DDMMYYYY')) AS day, 
            --You should considering using other way to truncate date from time, 
            --not convert too much,
            --at least you could use only to_varchar is enough
            place, 
            vehicle_id,
            SUM(meter_two_points) AS meter 
        FROM public.datatable 
        WHERE time >= '2015-09-05 00:00:00' 
            AND time <= '2015-09-05 23:00:00' 
            AND place=10 
        GROUP BY to_integer(to_varchar(time,'DDMMYYYY')), 
            vehicle_id, 
            place 
    )  
) AS a
GROUP BY range  
ORDER BY range 
LIMIT 10;       --why limit 10 here while you only have 10 ranges?

And as SQL order of operations , I keep wondering if PostgreSQL could GROUP BY after SELECT so group by could group with range column in your first query.

Answer 2

Here is an example of CASE in SELECT sentences, taken from the article "Declaraciones CASE en consultas OPEN SQL usando ABAP 7.4" , on ABAP.ar:

DATA: ls_vbak TYPE vbak,

 ld_vbeln LIKE vbak-vbeln.

PARAMETERS: p_vbeln like vbak-vbeln.

CONSTANTS: lc_name1(5) TYPE c VALUE 'name1',
 lc_name2(5) TYPE c VALUE 'name2',
 lc_name3(5) TYPE c VALUE 'name3'.

ld_vbeln = p_vbeln.

SELECT vbeln, vbtyp,
 CASE
 WHEN auart = 'ZAMA' THEN @lc_name1
 WHEN auart = 'ZACR' THEN @lc_name2
 ELSE @lc_name3
END AS ernam
FROM vbak
WHERE vbeln = @ld_vbeln
 INTO CORRESPONDING FIELDS of @ls_vbak.
ENDSELECT.

SELECT vbeln, vbtyp,
 CASE
 WHEN auart = 'ZAMA' THEN @lc_name1
 WHEN auart = 'ZACR' THEN @lc_name2
 ELSE @lc_name3
END AS ernam
FROM vbak
WHERE vbeln = @ld_vbeln
 INTO CORRESPONDING FIELDS of @ls_vbak.
ENDSELECT