GenericDAO for Android SQLite

GenericDAO.java

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class GenericDAO extends SQLiteOpenHelper {

    private static final String TAG = "GenericDAO";
    private static SQLiteDatabase db;
    private static String dName;
    private static String tName;
    private static String sql;
    public static final String KEY_ID = "_id";

    private static GenericDAO instance;
    
    private GenericDAO(Context ctx, String dbName, String sql, String tableName, int ver){
        super(ctx, dbName, null, ver);
        Log.i(TAG, "Creating or opening database [ " + dbName + " ].");
        GenericDAO.sql = sql;
        dName = dbName;
        tName = tableName;
    }
    
    public static GenericDAO getInstance(Context ctx, String dbName, String sql, String tableName, int ver){
        if(instance == null){
            instance = new GenericDAO(ctx, dbName, sql, tableName, ver);
            try{
                Log.i(TAG, "Creating or opening the database [ " + dbName + " ].");
                db = instance.getWritableDatabase();
            }catch(SQLiteException se){
                Log.e(TAG, "Cound not create and/or open the database [ " + dbName + " ] that will be used for reading and writing.", se);
            }
        }
        return instance;
    }

    public void close(){
        if(instance != null){
            Log.i(TAG, "Closing the database [ " + dName + " ].");
            db.close();
            instance = null;
        }
    }
    
    @Override
    public void onCreate(SQLiteDatabase db){
        Log.i(TAG, "Trying to create database table if it isn't existed [ " + sql + " ].");
        try{
            db.execSQL(sql);
        }catch(SQLException se){
            Log.e(TAG, "Cound not create the database table according to the SQL statement [ " + sql + " ].", se);
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
       Log.i(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data");
       try{
           db.execSQL("DROP TABLE IF EXISTS " + tName);
       }catch(SQLException se){
            Log.e(TAG, "Cound not drop the database table [ " + tName + " ].", se);
        }
       onCreate(db);
    }

    public long insert(String table, ContentValues values){
        return db.insert(table, null, values);
    }
    
    public Cursor get(String table, String[] columns){
        return db.query(table, columns, null, null, null, null, null);
    }
    
    public Cursor get(String table, String[] columns, long id){
        Cursor cursor =db.query(true, table, columns, KEY_ID + "=" + id, null, null, null, null, null);
        if (cursor != null) {
            cursor.moveToFirst();
        }
        return cursor;
    }
    
    public int delete(String table) {
        return db.delete(table, "1", null);
    }
    
    public int delete(String table, long id) {
        return db.delete(table, KEY_ID + "=" + id, null);
    }
    
    public int update(String table, long id, ContentValues values) {
        return db.update(table, values, KEY_ID + "=" + id, null);
    }
}

How to use it?
Notes.java

public class Notes {
    
    public static final String DATABASE_NAME = "data";
    public static final String DATABASE_TABLE = "notes";
    public static final int DATABASE_VERSION = 1;
    public static final String TABLE_CREATE =
        "create table notes (_id integer primary key autoincrement, "
                + "title text not null, body text not null);";
    
    public static final String COL_TITLE = "title";
    public static final String COL_BODY = "body";
    
    private int id;
    private String title;
    private String body;
    
    public int getId() {
        return id;
    }
    public String getTitle() {
        return title;
    }
    public String getBody() {
        return body;
    }
    public void setId(int id) {
        this.id = id;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public void setBody(String body) {
        this.body = body;
    }
    
    
}

    private String testCRUD(){
        
        String result="";
        Cursor cursor = null;
        String[] columns = new String[] {GenericDAO.KEY_ID, Notes.COL_TITLE, Notes.COL_BODY};
        
        GenericDAO dao = GenericDAO.getInstance(this, Notes.DATABASE_NAME, Notes.TABLE_CREATE, Notes.DATABASE_TABLE, Notes.DATABASE_VERSION);

        if(dao != null){
            
            ContentValues values = new ContentValues();
            values.put(Notes.COL_TITLE, "aaa");
            values.put(Notes.COL_BODY, "bbb");
            dao.insert(Notes.DATABASE_TABLE, values);
            
            values = new ContentValues();
            values.put(Notes.COL_TITLE, "ccc");
            values.put(Notes.COL_BODY, "ddd");
            dao.insert(Notes.DATABASE_TABLE, values);
            
            cursor = dao.get(Notes.DATABASE_TABLE, columns);
            
            
            int idColumn = cursor.getColumnIndex(GenericDAO.KEY_ID); 
            int titleColumn = cursor.getColumnIndex(Notes.COL_TITLE); 
            int bodyColumn = cursor.getColumnIndex(Notes.COL_BODY); 
            
            if(cursor != null){
                if(cursor.moveToFirst()){
                    
                    int count = cursor.getCount();
                    result = "there are " + count + " records.";
                    List<Notes> list = new ArrayList<Notes>();
                    
                    for(int i=0; i<count; i++){
                        
                        int id = cursor.getInt(idColumn); 
                        String title = cursor.getString(titleColumn); 
                        String body = cursor.getString(bodyColumn); 
                        
                        Notes notes = new Notes();
                        notes.setId(id);
                        notes.setTitle(title);
                        notes.setBody(body);
                        
                        list.add(notes);
                        
                        result += " " + i + ": " + "id=" + id + ", title=" + title + ", body=" + body + ";";
                        
                        cursor.moveToNext();
                    }
                }
            }
           
            result += " now update the second record.";
            
            values = new ContentValues();
            values.put(Notes.COL_TITLE, "eee");
            values.put(Notes.COL_BODY, "fff");
            dao.update(Notes.DATABASE_TABLE, 2, values);
            
            cursor.requery();
            cursor.close();

            result += " now delete first record.";
            
            dao.delete(Notes.DATABASE_TABLE, 1);
            
            result += " now delete all records.";
            
            dao.delete(Notes.DATABASE_TABLE);
            
            dao.close();
        }
        
        return result;
    }