mysql - SQL Self-Join Query in a complicated case -

-

i working on data sum up. different prices different periods.

on database looks 

itemid | time start | price | time end   01   | 2012-01-01 | $10   | null   01   | 2013-01-01 | $20   | 2013-06-01   01   | 2014-01-01 | $30   | null

and tricky part task askw me output form like

itemid | time start | time end   | price  01    | 2012-01-01 | 2013-01-01 | $10  01    | 2013-01-01 | 2013-06-01 | $20  01    | 2013-06-01 | 2014-01-01 | $10  01    | 2014-01-01 | null       | $30

i think should done statement using sql self join far don't have idea this.

especially have no idea how generate 'row 3' , 'row 4'

01 | 2013-06-01 | 2014-01-01 | $10

problem descriptions: each price related specific time slot. , there cases like:

case 1: if time slot has start time , end time, show it.(simple)   case 2 : if end time null, fill end time next start time.  case 3: (difficult one), row's start time comes the end time others row,it has match last time slot's end time.  , end time row should match start time of next time slot.

not highly efficient, should work:

select * ( select items1.itemid,        items1.timestart,        coalesce(items1.timeend, (select min(items2.timestart)                                    items items2                                   items2.itemid = items1.itemid                                     , items2.timestart > items1.timestart)),        items1.price   items items1 union select items3.itemid,        items3.timeend,        (select min(items4.timestart)           items items4         items4.itemid = items4.itemid           , items4.timestart > items3.timeend),        (select items5.price           items items5          items5.timestart = (select max(items6.timestart)                                      items items6                                     items6.itemid=items5.itemid                                       , items6.timestart < items3.timestart)        )   items items3  items3.timeend not null ) itemss order 2 asc

Comments

Post a Comment

Popular posts from this blog

python - TypeError: start must be a integer -

-
i trying draw 5 turtles, getting typeerror on line 25. here code: import turtle wn = turtle.screen() redrose = turtle.turtle() color = input("what background color be?") fillcolor_f = input("what color of rose be?") redrose.hideturtle() redrose.speed(30) redrose.penup() redrose.left(180) redrose.forward(175) redrose.right(90) redrose.forward(30) redrose.right(90) redrose.pendown() def drawrose(red): redrose.color("pink") redrose.fillcolor(fillcolor_f) redrose.fill(true) in range(red): redrose.forward(i) redrose.right(49) in range(5): drawrose(redrose) redrose.penup() redrose.forward(350) redrose.right(144) redrose.pendown() redrose.fill(false) drawrose(50) wn.bgcolor(color) i trying draw 5 roses, produces errors. doing in interactivepython.org. you recursively calling drawrose wrong parameter. on line 23 ( for in range(red): ) expect red integer...
Read more

c# - DevExpress RepositoryItemComboBox BackColor property ignored -

-
i have following code almost works properly; private void cbstatus_drawitem(object sender, listboxdrawitemeventargs e) { string item = e.item string; if (item != null) { switch (item) { case "1": e.appearance.forecolor = color.green; e.appearance.backcolor = color.green; break; case "2": e.appearance.forecolor = color.orange; e.appearance.backcolor = color.orange; break; case "3": e.appearance.forecolor = color.red; e.appearance.backcolor = color.red; break; } } } when dropdown shown, items forecolor correct, backcolor remains whatever backcolor of theme is; i.e. if i've got set dark theme, backcolor dark, cells in gridview, rather being green/orange/red. i've tried setting e.appearance.options.usebackcolor trying set e....
Read more

django - Creating multiple model instances in DRF3 -

-
1) create multiple model instances 1 api call, asked here: how create multiple model instances django rest framework? tried solution named in link, no success. i trying upload multiple files in 1 api call. result: files uploaded (only once overwrote perform_create) 1 instance created (if send 2 files, latter created instance). my code: class fileuploadserializer(serializers.modelserializer): def __init__(self, *args, **kwargs): many = kwargs.pop('many', true) super(fileuploadserializer, self).__init__(many=many, *args, **kwargs) class meta: model = fileupload read_only_fields = ('created', 'datafile', 'owner') class fileuploadviewset(viewsets.modelviewset): queryset = fileupload.objects.all() serializer_class = fileuploadserializer parser_classes = (multipartparser, formparser, ) def perform_create(self, serializer): file_list = self.request.data.getlist('file') ...
Read more