我得到这个错误

07-16 20:58:27.299: E/AndroidRuntime(14005): Caused by: android.database.sqlite.SQLiteException: no such table: strings: , while compiling: SELECT id, string FROM strings WHERE  id = ?

我有具有ID和String的StringDB类，用于将此类的对象存储到SQLite数据库中。请对其进行调试并提供解决方案。这是代码：

public class MySQLiteHelper extends SQLiteOpenHelper {


// Database Version
private static final int DATABASE_VERSION = 2;
// Database Name
private static final String DATABASE_NAME = "StringDB";

public MySQLiteHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION); 
}

@Override
public void onCreate(SQLiteDatabase db) {
    // SQL statement to create StringDB table
    String CREATE_StringDB_TABLE = "CREATE TABLE StringDBs ( " +
            "id INTEGER PRIMARY KEY AUTOINCREMENT, " +"string"+ "TEXT )";

    // create StringDBs table
    db.execSQL(CREATE_StringDB_TABLE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older StringDBs table if existed
    db.execSQL("DROP TABLE IF EXISTS StringDBs");

    // create fresh StringDBs table
    this.onCreate(db);
}
//---------------------------------------------------------------------

/**
 * CRUD operations (create "add", read "get", update, delete) StringDB + get all StringDBs + delete all StringDBs
 */

// StringDBs table name
private static final String TABLE_STRINGS = "strings";

// StringDBs Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_STRING= "string";

private static final String[] COLUMNS = {KEY_ID,KEY_STRING};

public void addStringDB(StringDB string){

    // 1. get reference to writable DB
    SQLiteDatabase db = this.getWritableDatabase();

    // 2. create ContentValues to add key "column"/value
    ContentValues values = new ContentValues();
    values.put(KEY_STRING, string.getString()); // get author

    // 3. insert
    db.insert(TABLE_STRINGS, // table
            null, //nullColumnHack
            values); // key/value -> keys = column names/ values = column values

    // 4. close
    db.close();
}

public StringDB getStringDB(int id){

    // 1. get reference to readable DB
    SQLiteDatabase db = this.getReadableDatabase();

    // 2. build query
    Cursor cursor =
            db.query(TABLE_STRINGS, // a. table
            COLUMNS, // b. column names
            " id = ?", // c. selections
            new String[] { String.valueOf(id) }, // d. selections args
            null, // e. group by
            null, // f. having
            null, // g. order by
            null); // h. limit

    // 3. if we got results get the first one
    if (cursor != null)
        cursor.moveToFirst();

    // 4. build StringDB object
    StringDB res=new StringDB();
    res.setId(Integer.parseInt(cursor.getString(0)));
    res.setString(cursor.getString(1));


    return res;
}

// Get All StringDBs
public List<StringDB> getAllStringDBs() {
    List<StringDB> StringDBs = new LinkedList<StringDB>();

    // 1. build the query
    String query = "SELECT  * FROM " + TABLE_STRINGS;

    // 2. get reference to writable DB
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(query, null);

    // 3. go over each row, build StringDB and add it to list
    StringDB StringDB = null;
    if (cursor.moveToFirst()) {
        do {
            StringDB = new StringDB();
            StringDB.setId(Integer.parseInt(cursor.getString(0)));
            StringDB.setString(cursor.getString(1));


            // Add StringDB to StringDBs
            StringDBs.add(StringDB);
        } while (cursor.moveToNext());
    }

    Log.d("getAllStringDBs()", StringDBs.toString());

    // return StringDBs
    return StringDBs;
}

 // Updating single StringDB
public int updateStringDB(StringDB StringDB) {

    // 1. get reference to writable DB
    SQLiteDatabase db = this.getWritableDatabase();

    // 2. create ContentValues to add key "column"/value
    ContentValues values = new ContentValues();
    values.put("strings", StringDB.getString()); // get author

    // 3. updating row
    int i = db.update(TABLE_STRINGS, //table
            values, // column/value
            KEY_ID+" = ?", // selections
            new String[] { String.valueOf(StringDB.getId()) }); //selection args

    // 4. close
    db.close();

    return i;

}

    // Deleting single StringDB
    public void deleteStringDB(StringDB StringDB) {

        // 1. get reference to writable DB
        SQLiteDatabase db = this.getWritableDatabase();

        // 2. delete
        db.delete(TABLE_STRINGS,
                KEY_ID+" = ?",
                new String[] { String.valueOf(StringDB.getId()) });

        // 3. close
        db.close();

        Log.d("deleteStringDB", StringDB.toString());

    }
}