Android sqlite - Return _id logged in Listview only one value selected using Where condition

Question

Good evening guys, I’m new here, I’m new to Android programming, but I decided to do my TCC, a project on Android. by doing alone, finding material on the Internet, without taking Android lessons, I’m going as well (or not), but stranded at a certain point.

I have a Listview that returns the data of the Sqlite database.

If I leave SELECT * FROM tbl_usuario; it brings me all registered users in the database, but I just wanted to let appear the user who logged in to the system.

i.e., I wanted to make a condition within Select, being "SELECT * FROM tbl_usuario WHERE _id = id that is logged in to the system.

but I can’t, I’ve already spent two days looking for a way to do, I’ve changed the structure of the code and I’m lost.

Well, my code is there.

public class Area_Usuario extends ActionBarActivity{
private String TABLE;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.area_usuario);
    TABLE = "tbl_usuario";


    DatabaseHandler db = new DatabaseHandler(this);
    Usuario usuario = new Usuario();
    SQLiteDatabase db1 = db.getReadableDatabase();
    String sql = ("SELECT * FROM " + TABLE);
    Cursor cursor= db1.rawQuery(sql,new String[]{String.valueOf(usuario.get_id())});
    String[] from = {"nome", "email", "senha"};
    int[] to = {R.id.Usuario_RowNome, R.id.Usuario_RowEmail, R.id.Usuario_RowSenha};
    ListView ltUsuario = (ListView) findViewById(R.id.listViewDadosUsuario);
    SimpleCursorAdapter ad = new SimpleCursorAdapter(getBaseContext(), R.layout.usuario_row, cursor, from, to, 1);
    ltUsuario.setAdapter(ad);
    db1.close();
   }
}

Answer 1

If you want to use the clause WHERE you will need to indicate it in Query:

String sql = ("SELECT * FROM " + TABLE + " WHERE _id = ?");
Cursor cursor= db1.rawQuery(sql,new String[]{String.valueOf(usuario.get_id())});

The ? is a 'placeholder' to receive the amount indicated in new String[]{String.valueOf(usuario.get_id())}

I suggest that as an alternative to db rawQuery., use the methods that Sqlitedatabase available for operations CRUD.

In the case of data reading use one of the variants of Sqlitedatabase.query

public Cursor query(String table, String[] columns, String selection, String[] selectionArgs,
                    String groupBy, String having, String orderBy)

Would look like this:

Cursor cursor = db1.query(TABLE, null, "_id = ?",
                           new String[]{String.valueOf(usuario.get_id())},null,null,null);