Question

I have an android application with a SQLite database and I am trying to implement a search interface. First of all, I realize that making a FTS database is the way to go, but I thought that I could use a LIKE statement and get similar results if I use wildcards. That way the interface can be tested and the backend updated later.

Here is how I build the query:

public Cursor getMatching(String query) {
    Cursor mCursor = db.query(false, TABLE, new String[] { KEY_ROWID,
            KEY_NAME }, KEY_NAME + " LIKE ?",
            new String[] { "%" + query + "%" }, null, null, null, null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

KEY_NAME is the text column that I want results for, and query is the lowercase string that I want to match against. I would expect that it would return results where the query appears anywhere in the name, case insensitive. However, what I observe is different. The results of querying “” (empty string):

Coch**** ****
Squi*** St*****
Owe** ****
Smi** Ca****
G. Bur** Jo******
Gr******* Brown

Now when I query “o”:

Owe** ****
G. Bur** Jo******
Gr******* Brown

Oddly enough, the first result is filtered out, although it contains an ‘o’. When I query “ow”:

Gr******* Brown

And finally when I query with “own”:

null

Here is the method I use to handle the cursor:

public static void logMatches(Context context, String query) {
    DBAdapter adapter = new DBAdapter(context);
    adapter.open();

    Cursor c = adapter.getMatching(query);

    if (c == null)
        return;

    while (c.moveToNext()) {
        String name = c.getString(c
                .getColumnIndex(DBAdapter.KEY_NAME));
        Log.d(TAG, name);
    }

    c.close();
    adapter.close();
}

Where DBAdapter contains the SQLiteOpenHelper. The context I am passing in comes from a ContentProvider by using the getContext() method.

I want to implement a FTS table eventually, but my database is quite small now so I hoped that I could implement similar functionality using existing tables for now. Is it possible to do what I want with the LIKE clause? Am I making an obvious mistake?

Answer 1

I did not tried it myself but fts actually implemented in SQLite for android. See for example here and here.

Ah, yes. Instead of while (c.moveToNext()) {} put do { } while (c.moveToNext())