android - ORMLite 使用谓词选择一些列

Question

我有包含某些字段的 ORMLite 数据库。我想从我从 webservice 获得的 id == id 表中选择标题。我喜欢这样:

 try {
    Dao<ProcessStatus,Integer> dao = db.getStatusDao(); 
    Log.i("status",dao.queryForAll().toString());
    QueryBuilder<ProcessStatus,Integer> query = dao.queryBuilder();
    Where where = query.where();
    String a = null;
    for(Order r:LoginActivity.orders) {
        //LoginActivity.orders - array of my objects which I get from webservice
        Log.i("database",query.selectRaw("select title from process_status").
            where().rawComparison(ProcessStatus.STATUS_ID, "=",
                       r.getProcess_status().getProccessStatusId()).toString());
    }
    Log.i("sr",a);
} catch (SQLException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

我这样试过，但我只得到了我的 id 集，没有标题。我试过这样:

Log.i("database", query.selectColumns(ProcessStatus.STATUS_TITLE).where().
    eq(ProcessStatus.STATUS_ID, r.getProcess_status().getProccessStatusId())
    .toString());

但我得到了相同的结果。我应该如何从数据库中获取数据？

Answer 1

要从表中选择特定字段，您可以这样做:

String result = "";
try {
    GenericRawResults<String[]> rawResults = yourDAO.queryRaw("select " +
        ProcessStatus.STATUS_TITLE +" from YourTable where "+ 
        ProcessStatus.STATUS_ID + " = " + 
        r.getProcess_status().getProccessStatusId());
    List<String[]> results = rawResults.getResults();
    // This will select the first result (the first and maybe only row returned)
    String[] resultArray = results.get(0);
    //This will select the first field in the result which should be the ID
    result = resultArray[0];
} catch (Exception e) {
    e.printStackTrace();
}

希望这对您有所帮助。