Question

I’m trying to feed a listview with a custom cursorAdapter.

I get this error : 03-16 03:25:39.968: E/AndroidRuntime(14552): Caused by: android.database.sqlite.SQLiteException: no such column: _id: , while compiling: SELECT _id, content_note FROM notes

at this line values.put(DataBaseHelper.DATABASEBASE_CONTENT_NOTE, note.getContent());

Here are my 2 Connections classes

    package com.android.database;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DataBaseHelper extends SQLiteOpenHelper{

    private static final String DATABASE_NAME = "db";
    public static final String DATABASE_TABLE_NOTE = "notes";
    public static final String DATABASE_ID_NOTE = "_id";
    public static final String DATABASE_CONTENT_NOTE = "content_note";

    public DataBaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + DATABASE_TABLE_NOTE + " (" + DATABASE_ID_NOTE + " INTEGER PRIMARY KEY, " + DATABASE_CONTENT_NOTE + " TEXT);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        android.util.Log.w("Constants", "Maj de la base, suppression de toutes les anciennes donnees");
        db.execSQL("DROP TABLE IF EXISTS Notes");
        onCreate(db);
    }

}



    package com.android.database;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;

public class NoteDataSource{

    private SQLiteDatabase database;
    private DataBaseHelper dbHelper;
    private String[] allColumns = { DataBaseHelper.DATABASE_ID_NOTE,
            DataBaseHelper.DATABASE_CONTENT_NOTE };

    public NoteDataSource(Context context) {
        dbHelper = new DataBaseHelper(context);
    }


    public void open() throws SQLException {
        database = dbHelper.getWritableDatabase();
    }

    public void close() {
        dbHelper.close();
    }

    public Cursor createNoteTop(String note) {

        //recuperer le bon id

//      int idNote = getFirstId().getId();
        int idNote = 1 ;

        ContentValues values = new ContentValues();
        values.put(DataBaseHelper.DATABASE_ID_NOTE, idNote);
        values.put(DataBaseHelper.DATABASE_CONTENT_NOTE, note);
        long insertId = database.insert(DataBaseHelper.DATABASE_TABLE_NOTE, null,
                values);
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, DataBaseHelper.DATABASE_ID_NOTE + " = " + insertId, null,
                null, null, null);
        cursor.moveToFirst();
        return cursor;
    }

    public Cursor createNoteBottom(String note) {

        //recuperer le bon id

        int idNote = getLastId().getId();

        ContentValues values = new ContentValues();
        values.put(DataBaseHelper.DATABASE_ID_NOTE, idNote);
        values.put(DataBaseHelper.DATABASE_CONTENT_NOTE, note);
        long insertId = database.insert(DataBaseHelper.DATABASE_TABLE_NOTE, null,
                values);
        // To show how to query
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, DataBaseHelper.DATABASE_ID_NOTE + " = " + insertId, null,
                null, null, null);
        cursor.moveToFirst();
        return cursor;
    }

    public void deleteNote(Note note) {
        long id = note.getId();
        System.out.println("Note deleted with id: " + id);
        database.delete(DataBaseHelper.DATABASE_TABLE_NOTE, DataBaseHelper.DATABASE_ID_NOTE
                + " = " + id, null);
    }

    public Cursor getAllNotes() {
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, null, null, null, null, null);
        return cursor;
    }

    private Note getFirstId(){
        Note notes = new Note();
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, null, null, null, null, null);
        cursor.moveToFirst();
        notes = cursorToNote(cursor);

        return notes;

    }

    private Note getLastId(){

        Note notes = new Note();
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, null, null, null, null, null);
        cursor.moveToLast();
        notes = cursorToNote(cursor);

        return notes;

    }

    private Note cursorToNote(Cursor cursor) {
        Note note = new Note();
        note.setId(cursor.getInt(0));
        note.setContent(cursor.getString(1));
        return note;
    }




}

This must be simple and come from the fact that I already created base with other name fields and it doesn’t upgrade.

Thanks.

Answer 1

This must be simple and come from the fact that I already created base with other name fields and it doesn’t upgrade.

I guess you are right. You should increase the version number whenever you change the database. Then you can put code in onUpgrade that can handle the transition.

private static final int DATABASE_VERSION = 2;
public DataBaseHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

The schema for onUpgrade is usually like this

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // it all started this way
    if (oldVersion < 1) {
        db.execSQL("CREATE TABLE supertable...");
    }

    // in version 2 I decided that I need another table
    if (oldVersion < 2) {
        db.execSQL("CREATE TABLE cooltable...");
    }

    // in version 3 I decided that the table is not required anymore
    if (oldVersion < 3) {
        db.execSQL("DROP TABLE cooltable...");
    }
    // remember to increase DATABASE_VERSION if you add steps here.
}

That upgrade schema will also allow users that have your app installed to upgrade the app to new versions without getting corrupted databases.