android - How to generate database with table of variable number of columns? -

-

in android app, need temporarily store data in form of table such follows:

id | column 1 | column 2 | ... | column n

the data downloaded server whenever users press button. however, data table doesn't have fix number of column (as row) every time user downloads server. example, server may send data 3 columns first time. might send data 5 columns second time, etc...

given scenario, think database right data structure use. plan create database, add , delete tables necessary. have been reading various tutorials on android database (one example 1 http://www.codeproject.com/articles/119293/using-sqlite-database-with-android#). seems me cannot create new table variable number of columns using sqlite database. correct? in oncreate(sqlitedatabase db) method, "create table" command must specified known number of columns , data types. provide several "create table" commands, each different number of columns seems crude. there way create database tables variable number of columns on fly?

another alternative using several hash tables, each storing 1 column of data table. i'm considering approach if database approach not possible. better suggestion welcomed.

there no such thing variable number of columns in sqlite data base. also, adding , deleting tables dynamically seems horrible hack.

it sounds want store array of values associated id. suggest think in terms of rows, not columns. use table structure (id, index, value); each array of values returned server results in many rows necessary store values.


Comments

Post a Comment

Popular posts from this blog

c# - SVN Error : "svnadmin: E205000: Too many arguments" -

-
i trying reposotries using c# code process svncommand = null; var psi = new processstartinfo("svnadmin"); psi.redirectstandardoutput = true; psi.redirectstandarderror = true; psi.useshellexecute = false; psi.arguments= @"dump c:\repositories\myrepo > c:\temp\myrepodumpfile.dump"; using (svncommand = process.start(psi)) { var myoutput = svncommand.standardoutput; var myerror = svncommand.standarderror; debug.write("output :" + environment.newline + environment.newline + myoutput.readtoend() + environment.newline + "error :" + environment.newline + environment.newline + myerror.readtoend()); svncommand.close(); } when use dump command commandline svnadmin dump c:\repositories\myrepo > c:\temp\myrepodumpfile.dump it works fine when try ...
Read more

c# - Copy ObservableCollection to another ObservableCollection -

-
how copy observablecollection item observablecollection without reference of first collection? here observablecollection item value changes affecting both collections. code private observablecollection<ratemodel> _allmetalrate = new observablecollection<ratemodel>(); private observablecollection<ratemodel> _metalrateondate = new observablecollection<ratemodel>(); public observablecollection<ratemodel> allmetalrate { { return this._allmetalrate; } set { this._allmetalrate = value; notifypropertychanged("metalrate"); } } public observablecollection<ratemodel> metalrateondate { { return this._metalrateondate; } set { this._metalrateondate = value; notifypropertychanged("metalrateondate"); } } foreach (var item in metalrateondate) allmetalrate.add(item); what causing , how can solve it? you need clone object referenced item before it's a...
Read more

All overlapping substrings matching a java regex -

-
is there api method returns (possibly overlapping) substrings match regular expression? for example, have text string: string t = 04/31 412-555-1235; , , have pattern: pattern p = new pattern("\\d\\d+"); matches strings of 2 or more characters. the matches are: 04, 31, 412, 555, 1235. how overlapping matches? i want code return: 04, 31, 41, 412, 12, 55, 555, 55, 12, 123, 1235, 23, 235, 35. theoretically should possible -- there obvious o(n^2) algorithm enumerates , checks substrings against pattern. edit rather enumerating substrings, safer use region(int start, int end) method in matcher . checking pattern against separate, extracted substring might change result of match (e.g. if there non-capturing group or word boundary check @ start/end of pattern). edit 2 actually, it's unclear whether region() expect zero-width matches. specification vague, , experiments yield disappointing results. for example: string line = "xx90xx"; strin...
Read more