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POProblem With Updating Database in Android app
 

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  1. POProblem With Updating Database in Android app
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    <p>I'm having a bit of trouble understand what to do if I want to upgrade a database with an app update, though my case is a bit unique. The starting database (in the assets folder) has a few tables that have records in them already, so it just directly copies the entire database to the data/data/<em>package</em>/databases/ folder. When I want to do an update I want some some tables to keep their data, but I want other tables to be dropped and added from the updated database.</p> <p>I'm assuming I put my code in OnUpgrade, but I'm not sure what to put...I can back up the data in the table, but I'm not sure how copy it back.</p> <p>Here's some snippets of my code.</p> <pre><code>public class DataBaseHelper extends SQLiteOpenHelper{ //The Android's default system path of your application database. private static String DB_PATH = "/data/data/package/databases/"; private static String DB_NAME = "drink.db"; private static final int DATABASE_VERSION = 2; SQLiteDatabase myDataBase; private final Context myContext; public DataBaseHelper(Context context) { super(context, DB_NAME, null, DATABASE_VERSION); this.myContext = context; } public void createDataBase() throws IOException{ boolean dbExist = checkDataBase(); if(dbExist){ //do nothing database already exists }else{ try { copyDataBase(); } catch (IOException e) { throw new RuntimeException(e.getMessage()); } } } private boolean checkDataBase(){ SQLiteDatabase checkDB = null; try{ String myPath = DB_PATH + DB_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); }catch(SQLiteException e){ //database does't exist yet. } if(checkDB != null){ checkDB.close(); } return checkDB != null ? true : false; } private void copyDataBase() throws IOException{ //Open your local db as the input stream InputStream myInput = myContext.getAssets().open(DB_NAME); // Path to the just created empty db String outFileName = DB_PATH + DB_NAME; //Open the empty db as the output stream OutputStream myOutput = new FileOutputStream(outFileName); //transfer bytes from the inputfile to the outputfile byte[] buffer = new byte[1024]; int length; while ((length = myInput.read(buffer))&gt;0){ myOutput.write(buffer, 0, length); } //Close the streams myOutput.flush(); myOutput.close(); myInput.close(); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { if (newVersion &gt; oldVersion) { } } } </code></pre> <p>Thanks again!</p>
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