查询有2个Where子句

public Boolean login(String username, String password) throws SQLException {
    Cursor mCursor = db.query(TABLE_USERS, new String[] { ID,
            KEY_NAME, KEY_USERNAME}, KEY_USERNAME + "="
            + "'"+username+"'", KEY_PASSWORD + "="
            + "'"+password+"'", null, null, null, null, null);

    if (mCursor.moveToFirst()) {
        return true;
    }
    return false;
}