java - How to exclude date stored in database to a range? -

-

i have table "holidays" in database, contains range of days when it's holidays, defined 2 column : start & end.

holidays (id, name, start, end)

now, if have in input, 2 dates (from & to), i'd list dates not in holidays.

suppose holidays 2012/06/05 2012/06/20, , request :

  1. from=2012/06/01, to=2012/06/10 ; result 01, 02, 03, 04
  2. from=2012/06/01, to=2012/06/22 ; result 01, 02, 03, 04, 21, 22
  3. from=2012/06/15, to=2012/06/22 ; result 21, 22

but can't figure out how list of "opened" days without hitting database every days requested in range from->to.

how do?

thanks help!

there many solutions, pretty depends on how many entries have in database , how many requests do. if making lot of request, can thing this:

-> create boolean array determine if day holiday or not;    first element points predefined date (e.g. 1.1.2012),     second element 2.1.2012, etc. -> initialize array 0 -> each holiday   -> make loop initialized holiday start date ,      expression each pass: current date = holiday start date + 1 day     -> covert current date index (number of days since start date - 1.1.2012)     -> set array[index] 1

now should have simple array containing 0 non-holiday day , 1 holiday day

for each query (request) do

-> loop goes request start date request end date    -> convert current date index (number of days since 1.1.2012)    -> check if array[index] 0 or 1

but keep in mid, solution ok many query (requests). if have first part every request, solution not make sense , better write sql query.


Comments

Post a Comment

Popular posts from this blog

django - How can I change user group without delete record -

-
on website user have 1 group. , user can change group. it's made user.groups.clear() and user.groups.add(new_group) but it's not efficient, because there 2 sql query: delete, insert. how can change group update query? user , group related each other using manytomanyfield . means intersection table exists relating both entities, , if don't specify model map (using through attribute) django creates 1 you. looking @ sources django.contrib.auth.models see that's case. fortunatly, can access intermediary model using through attribute of manager (in case, user.groups.through ). can use regular model. example: >>> alice = user.objects.create_user('alice', 'alice@example.com', 'alicepw') >>> employee = group.objects.create(name='employee') >>> manager = group.objects.create(name='manager') >>> alice.groups.add(employee) >>> alice.groups.all() [<group: employee...
Read more

java - Need to add SOAP security token -

-
i need set custom soap header attribute on jax-ws generated webservice client. case webservice calls must go through proxy server requiring specific token (recieved web request header) present in soap request header. e.g.: 1 carserviceservice service = null; 2 service = new carserviceservice(new url(url), new qname(qname); 3 carserviceendpoint port = service.getcarserviceport(); it seems in line 3 wsdl retrieved , call fails due missing security token. 1 point direction on how done? a detailed example has been mentioned here: creating , deploying jax-ws web service on tomcat 6 this article shows how create , use security token .
Read more

java - EclipseLink JPA Object is not a known entity type -

-
i have strange problem eclipselink , object want persist. have 1 object (keypointlistimpl) stores object keypointimpl in list. persisting keypointimpl objects works great if try persist keypointlistimpl object java.lang.illegalargumentexception says object keypointimpl isn't known entity type. here keypointimpl code: @entity @table(name="keypoints") public class keypointimpl implements keypoint { @id @generatedvalue(strategy = generationtype.identity) private int id; @enumerated(enumtype.string) private detectortype keypointtype; private float x; private float y; private float size; private float angle; private float response; private int octave; private int classid; ... } here keypointlistimpl code: @entity @table(name="keypointlists") public class keypointlistimpl implements keypointlist { @id @generatedvalue(strategy = generationtype.identity) private int id; @onetoone(cascade={ca...
Read more