Django的最大

Question

在SQL提示，當我嘗試這個辦法：

select app_name, max(SNAP_SNAPINFO.id) 
from SNAP_SNAPTOPO inner JOIN SNAP_SNAPINFO ON SNAP_SNAPTOPO.SNP_ID = SNAP_SNAPINFO.ID 
where app_name in ('invoiceserv','cal_host') and stream = 'live' and snp_id <= 135353 
group by app_name; 

我得到這個：

cal_host 126972 
invoiceserv 127240 

在Django我不能夠進行編程，以相同的需求

>>> st = SnapTopo.objects.filter(app_name__in=['invoiceserv','cal_host'], 
...       snp__stream='live', 
...       snp__id__lte=125353).values('app_name', 'snp__id').\ 
...       annotate(snpid=Max('snp__id')) 
>>> print st.query 
SELECT "SNAP_SNAPTOPO"."APP_NAME", "SNAP_SNAPTOPO"."SNP_ID", MAX("SNAP_SNAPTOPO"."SNP_ID") AS "SNPID" FROM "SNAP_SNAPTOPO" LEFT OUTER JOIN "SNAP_SNAPINFO" ON ("SNAP_SNAPTOPO"."SNP_ID" = "SNAP_SNAPINFO"."ID") WHERE ("SNAP_SNAPINFO"."STREAM" = live AND "SNAP_SNAPTOPO"."APP_NAME" IN (invoiceserv, cal_host) AND "SNAP_SNAPTOPO"."SNP_ID" <= 125353) GROUP BY "SNAP_SNAPTOPO"."APP_NAME", "SNAP_SNAPTOPO"."SNP_ID", "SNAP_SNAPTOPO"."APP_NAME", "SNAP_SNAPTOPO"."SNP_ID", "SNAP_SNAPINFO"."SNP_TS", "SNAP_SNAPINFO"."SNP_NUMBER" ORDER BY "SNAP_SNAPINFO"."SNP_TS" ASC, "SNAP_SNAPINFO"."SNP_NUMBER" DESC 
>>> print st 
[{'snpid': 72538, 'app_name': u'cal_host', 'snp__id': 72538}, {'snpid': 74723, 'app_name': u'invoiceserv', 'snp__id': 74723}, {'snpid': 89231, 'app_name': u'cal_host', 'snp__id': 89231}, {'snpid': 91960, 'app_name': u'cal_host', 'snp__id': 91960}, {'snpid': 96325, 'app_name': u'invoiceserv', 'snp__id': 96325}, {'snpid': 100656, 'app_name': u'cal_host', 'snp__id': 100656}, {'snpid': 104496, 'app_name': u'invoiceserv', 'snp__id': 104496}, {'snpid': 106982, 'app_name': u'cal_host', 'snp__id': 106982}, {'snpid': 120957, 'app_name': u'cal_host', 'snp__id': 120957}] 

我想要一個模擬前面提到的SQL語句行爲的django代碼。我錯過了什麼？

Answer 1

截至目前，我做如下：

>>> for appname in ('invoiceserv', 'cal_host'): 
...  max_snp_id = SnapTopo.objects.filter(app_name=appname, snp__stream='live', 
...        snp__id__lte=125353).aggregate(Max('snp__id')) 
...  print appname, max_snp_id 
... 
invoiceserv {'snp__id__max': 104496} 
cal_host {'snp__id__max': 120957} 

我使用Django的API

尋找一個最佳的解決方案