Pourquoi cette requête me donne un curseur vide?

Question

im faire une application Android, et j'ai un DB local avec MyDBAdapter

insérer un grand nombre de positions dans mon DB avec ce code (myPositions nantis beaucoup de positions sur elle)

for (int i=0;i<myPositions.size();i++) 
     { 
      MyApplication.getDatabaseAdapter().createPosition(myPositions.get(i).getIdposition(),myPositions.get(i).getLatitude(),myPositions.get(i).getLongitude(),myPositions.get(i).getpositiontimeFormated(),myPositions.get(i).getFk_email()); 
     } 

ok , mais quand j'essaie d'obtenir les positions d'un utilisateur qui a beaucoup de possitions je reçois un curseur vide ..... voici le code que j'utilise pour obtenir le curseur avec les positions de l'utilisateur, j'appelle retrievePositionsByEmail, et cette fonction appelle fetchPositionsByEmail, mais fetchPositionsByEmail retourne en EMPTY CURSOR

public Cursor fetchPositionsByEmail(String email) throws SQLException { 

    Cursor mCursor = mDb.query(true, "position", new String[] {"idposition", "latitude", "longitude", "timestamp", "fk_email"} 
     , "fk_email" + "='" + email+"'", null, null, null, null, null); 

    //Cursor mCursor = mDb.query(true, "position", new String[] {"idposition", "latitude", "longitude", "timestamp", "fk_email"} 
    //, "fk_email=?", new String[] { email } , null, null, null, null); 
    if (mCursor != null) { 
     mCursor.moveToFirst(); 
    } 
    return mCursor; 
} 


public List<Position> retrievePositionsByEmail(String email) 
{ 
    List <Position> positions=new ArrayList<Position>(); 
    Cursor result=fetchPositionsByEmail(email); 
    if(result.moveToFirst()){ 
     do{ 
      positions.add(new Position(result.getString(result.getColumnIndexOrThrow("idposition")), 
        result.getString(result.getColumnIndexOrThrow("latitude")), 
        result.getString(result.getColumnIndexOrThrow("longitude")), 
        result.getString(result.getColumnIndexOrThrow("timestamp")), 
        result.getString(result.getColumnIndexOrThrow("fk_email")))); 
     }while(result.moveToNext()); 
    } 
    return positions; 
} 

et voici le code complet de mon adaptateur DB local:

public class MyDbAdapter { 

    private static final String TAG = "NotesDbAdapter"; 
    private DatabaseHelper mDbHelper; 
    private SQLiteDatabase mDb; 
    private static final String DATABASE_NAME = "gpslocdb"; 
    private static final String PERMISSION_TABLE_CREATE = "CREATE TABLE permission (fk_email1 varchar, fk_email2 varchar, validated tinyint, hour1 time default '08:00:00', hour2 time default '20:00:00', date1 date, date2 date, weekend tinyint default '0', fk_type varchar, PRIMARY KEY (fk_email1,fk_email2))"; 
    private static final String USER_TABLE_CREATE = "CREATE TABLE user (email varchar, password varchar, fullName varchar, mobilePhone varchar, mobileOperatingSystem varchar, PRIMARY KEY (email))"; 
    private static final String POSITION_TABLE_CREATE = "CREATE TABLE position (idposition bigint, latitude varchar, longitude varchar, timestamp datetime, fk_email varchar, PRIMARY KEY (idposition))"; 


    private static final int DATABASE_VERSION = 2; 

    private final Context mCtx; 

    private static class DatabaseHelper extends SQLiteOpenHelper { 

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

     @Override 
     public void onCreate(SQLiteDatabase db) { 
      db.execSQL("DROP TABLE IF EXISTS user"); 
      db.execSQL("DROP TABLE IF EXISTS permission"); 
      db.execSQL("DROP TABLE IF EXISTS position"); 
      db.execSQL(PERMISSION_TABLE_CREATE); 
      db.execSQL(USER_TABLE_CREATE); 
      db.execSQL(POSITION_TABLE_CREATE); 
     } 

     @Override 
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
      //db.execSQL("DROP TABLE IF EXISTS user"); 
      //db.execSQL("DROP TABLE IF EXISTS permission"); 
      //onCreate(db); 
     } 

     @Override 
     public void onOpen(SQLiteDatabase db) { 
      super.onOpen(db); 
      //onCreate(db); 
     } 
     public void clearDb(SQLiteDatabase db){ 
      db.execSQL("DROP TABLE IF EXISTS user"); 
      db.execSQL("DROP TABLE IF EXISTS permission"); 
      db.execSQL("DROP TABLE IF EXISTS position"); 
      onCreate(db); 
     } 
     public void deleteUser(SQLiteDatabase db, String email) 
     { 
      db.execSQL("DELETE FROM user Where email='"+email+"'"); 
     } 
     public void deletePermission(SQLiteDatabase db, String email) 
     { 
      db.execSQL("DELETE FROM permission Where fk_email2='"+email+"'"); 
     } 
    } 

    /** 
    * Constructor - takes the context to allow the database to be 
    * opened/created 
    * 
    * @param ctx the Context within which to work 
    */ 
    public MyDbAdapter(Context ctx) { 
     this.mCtx = ctx; 
    } 

    /** 
    * Open the database. If it cannot be opened, try to create a new 
    * instance of the database. If it cannot be created, throw an exception to 
    * signal the failure 
    * 
    * @return this (self reference, allowing this to be chained in an 
    *   initialization call) 
    * @throws SQLException if the database could be neither opened or created 
    */ 
    public MyDbAdapter open() throws SQLException { 
     mDbHelper = new DatabaseHelper(mCtx); 
     mDb = mDbHelper.getWritableDatabase(); 
     return this; 
    } 

    public void close() { 
     //clearDB(); 
     mDbHelper.close(); 
    } 

    public long createUser(String email, String password, String fullName, String mobilePhone, String mobileOperatingSystem) 
    { 
     ContentValues initialValues = new ContentValues(); 
     initialValues.put("email",email); 
     initialValues.put("password",password); 
     initialValues.put("fullName",fullName); 
     initialValues.put("mobilePhone",mobilePhone); 
     initialValues.put("mobileOperatingSystem",mobileOperatingSystem); 
     return mDb.insert("user", null, initialValues); 
    } 
    public long createPermission(String email1, String email2, String validated, String hour1, String hour2, 
      String date1, String date2, String weekend, String fk_type) 
    { 
     ContentValues initialValues = new ContentValues(); 
     initialValues.put("fk_email1",email1); 
     initialValues.put("fk_email2",email2); 
     initialValues.put("validated",validated); 
     initialValues.put("hour1",hour1); 
     initialValues.put("hour2",hour2); 
     initialValues.put("date1",date1); 
     initialValues.put("date2",date2); 
     initialValues.put("weekend",weekend); 
     initialValues.put("fk_type",fk_type); 
     return mDb.insert("permission", null, initialValues); 
    } 
    public long createPosition(String idposition, String latitude, String longitude, String timestamp, String fk_email) 
    { 
     ContentValues initialValues = new ContentValues(); 
     initialValues.put("idposition",idposition); 
     initialValues.put("latitude",latitude); 
     initialValues.put("longitude",longitude); 
     initialValues.put("timestamp",timestamp); 
     initialValues.put("fk_email",fk_email); 
     return mDb.insert("position", null, initialValues); 
    } 



    public void clearDB() { 
     mDbHelper.clearDb(mDb);   
    } 

    public Cursor fetchAllUsers() { 

     return mDb.query("user", new String[] {"email", "password", "fullName", "mobilePhone", "mobileOperatingSystem"}, null, null, null, null, null); 
    } 
    public Cursor fetchAllPermissions() { 

     return mDb.query("permission", new String[] {"fk_email1", "fk_email2", "validated", "hour1", "hour2", "date1", "date2", "weekend", "fk_type"}, null, null, null, null, null); 
    } 

    public Cursor fetchUser(String email) throws SQLException { 

     Cursor mCursor = mDb.query(true, "user", new String[] {"email", "password", "fullName", "mobilePhone", "mobileOperatingSystem"} 
      , "email" + "=" + email, null, null, null, null, null); 
     if (mCursor != null) { 
      mCursor.moveToFirst(); 
     } 
     return mCursor; 
    } 

    public Cursor fetchPositionsByEmail(String email) throws SQLException { 

     Cursor mCursor = mDb.query(true, "position", new String[] {"idposition", "latitude", "longitude", "timestamp", "fk_email"} 
      , "fk_email" + "='" + email+"'", null, null, null, null, null); 

     //Cursor mCursor = mDb.query(true, "position", new String[] {"idposition", "latitude", "longitude", "timestamp", "fk_email"} 
     //, "fk_email=?", new String[] { email } , null, null, null, null); 
     if (mCursor != null) { 
      mCursor.moveToFirst(); 
     } 
     return mCursor; 
    } 

    public List<Friend> retrieveAllFriends() 
    { 
     List <Friend> friends=new ArrayList<Friend>(); 
     Cursor result=fetchAllUsers(); 
     if(result.moveToFirst()){ 
      do{ 
       friends.add(new Friend(result.getString(result.getColumnIndexOrThrow("email")),result.getString(result.getColumnIndexOrThrow("password")), result.getString(result.getColumnIndexOrThrow("fullName")),result.getString(result.getColumnIndexOrThrow("mobilePhone")),result.getString(result.getColumnIndexOrThrow("mobileOperatingSystem")))); 
      }while(result.moveToNext()); 
     } 
     return friends; 
    } 
    public List<Permission> retrieveAllPermissions() 
    { 
     List <Permission> permissions=new ArrayList<Permission>(); 
     Cursor result=fetchAllPermissions(); 
     if(result.moveToFirst()){ 
      do{ 
       permissions.add(new Permission(result.getString(result.getColumnIndexOrThrow("fk_email1")), 
         result.getString(result.getColumnIndexOrThrow("fk_email2")), 
         Integer.parseInt(result.getString(result.getColumnIndexOrThrow("validated"))), 
         result.getString(result.getColumnIndexOrThrow("hour1")), 
         result.getString(result.getColumnIndexOrThrow("hour2")), 
         result.getString(result.getColumnIndexOrThrow("date1")), 
         result.getString(result.getColumnIndexOrThrow("date2")), 
         Integer.parseInt(result.getString(result.getColumnIndexOrThrow("weekend"))), 
         result.getString(result.getColumnIndexOrThrow("fk_type")))); 
      }while(result.moveToNext()); 
     } 
     return permissions; 
    } 

    public List<Position> retrievePositionsByEmail(String email) 
    { 
     List <Position> positions=new ArrayList<Position>(); 
     Cursor result=fetchPositionsByEmail(email); 
     if(result.moveToFirst()){ 
      do{ 
       positions.add(new Position(result.getString(result.getColumnIndexOrThrow("idposition")), 
         result.getString(result.getColumnIndexOrThrow("latitude")), 
         result.getString(result.getColumnIndexOrThrow("longitude")), 
         result.getString(result.getColumnIndexOrThrow("timestamp")), 
         result.getString(result.getColumnIndexOrThrow("fk_email")))); 
      }while(result.moveToNext()); 
     } 
     return positions; 
    } 


    public void deleteUser(String email) throws SQLException 
    { 
     mDbHelper.deleteUser(mDb, email); 
    } 
    public void deletePermission(String email) throws SQLException 
    { 
     mDbHelper.deletePermission(mDb, email); 
    } 

} 

Answer 1

Le problème, je pense, est à utiliser:

"fk_email" + "='" + email+"'" 

pour la sélection args. La chaîne de messagerie a probablement des caractères qui doivent être échappés pour être une syntaxe SQL légale. Voyez si cela fonctionne mieux:

StringBuilder sb = new StringBuilder("fk_email="); 
DatabaseUtils.appendEscapedSQLString(sb, email); 
Cursor mCursor = mDb.query(
    true, 
    "position", 
    new String[] {"idposition", "latitude", "longitude", "timestamp", "fk_email"}, 
    sb.toString(), 
    null, null, null, null, null); 

StringBuilder sb = new StringBuilder("fk_email="); 
DatabaseUtils.appendEscapedSQLString(sb, email); 
Cursor mCursor = mDb.query(
    true, 
    "position", 
    new String[] {"idposition", "latitude", "longitude", "timestamp", "fk_email"}, 
    sb.toString(), 
    null, null, null, null, null);