Working with SQLite in Android. Tools and stuff.

The Notepad tutorial uses sqlite to store the users entered notes. This is a single table, so this method query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) was fine.

It takes a single table name and some params for the other clauses. To use more than one table I used the rawQuery(String sql, String[] selectionArgs) method.

This takes arbitrary sql (union in my case) along with values to bind to any ? that you used.

I have removed the SQLiteOpenHelper from the code also. This opens and creates your database and handles upgrading the database following schema changes. Overall I found this cumbersome and have switched to moving the database file from the device (emulator) to my pc. I then query it using SQLite 2009 Pro. I got it here. Excellent query analyzer type tool. I make my changes here (schema and data) and then push this back to the device when I am ready to test with the app. The pushing is done with Eclipses DDMS perspective. If you work this way you don't need the SQLiteOpenHelper and can just run with a SQLiteDatabase instead. This is more straightforward.

Comments

Post a Comment

Popular posts from this blog

AutoCompleteTextView backed with data from SQLite in Android

Image
This is a handy piece of code. As your database gets bigger you can allow the user to pick the correct value by typing. If the db gets very big, you can always increase the threshold, so that the query does not run until there will be a suitably sized resultset returned. Running it at a threshold of 1 is fine for very small resultsets.  Here is the code you need to back your AutoCompleteTextView with a cursor adapter. @Override protected void onResume() { super.onResume(); text = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView1); final AdapterHelper h = new AdapterHelper(this); Cursor c = h.getAllResults(); startManagingCursor(c); String[] from = new String[] { "val" }; int[] to = new int[] { android.R.id.text1 }; CursorAdapter adapter = new MyCursorAdapter(this, android.R.layout.simple_dropdown_item_1line, c, from, to); adapter.setFilterQueryProvider(new FilterQueryProvider() { public Cursor runQuery(Cha...
Read more

Building a choropleth map for Irish agricultural data

I wanted to create a choropleth map  using Irish data. The Irish Government has made a large quantity of data available at data.gov.ie. The set I chose was for Bovine TB across Ireland over a number of years. You can get geojson for a variety of countries and Ireland's county boundaries are available. All I had to do was get the data labels to match. In the data some counties are split into 2 parts. I merged and summed these data points to get the choropleth to work with normal county boundaries. You can see the results here . A link to the github is included at the top of the notebook.
Read more

Using Statistics to Hire Developers

The Interview I was interviewing a developer for a mid level position today and he turned out to be not up to scratch. The CV looked pretty good, but when I dug in with some fundamental Java questions he was found wanting. Not an unusual occurrence, but still costly. It took 30 minutes of my time, his time and a number of other people were involved to get the process to this stage. I wondered if there might be a way to remove some of the candidate CVs from the batch before we do the costly part of interviewing. Spam or Ham Classifying CVs could be considered like the Spam/Ham problem. Apache SpamAssassin is a good example of a spam classifier. It can probably be made to classify CVs - or at least try, but it is written in C, I think and that is not my thing any more. This looks interesting, so I forked it, converted it to eclipse and started the process of making it build with Maven. First I am going to try this out with spam and ham email, then will try it for other text p...
Read more