Question

我正在尝试将json对象放在sqlite数据库中

private void addList(String info){
    try {        
        JSONObject reader=new JSONObject(info);

        String COMMAND = reader.getString("COMMAND");
        String PARAMS = reader.getString("PARAMS");

        int id = vpictures.InsertList(COMMAND,info);

    } catch (Exception e){
        if (DEBUG_FLAG)Log.d("Log1 ", "adding Exception :"+ e.getMessage());
    }
    return;
}

json对象info看起来像这样

{
    "COMMAND":"ADD_NEW",
    "PARAMS":{
        "deviceID":"1234",
        "custID":"41701",
        "description":"Ddd",        
        "colTranType":"ABS",        
        }
}

这是我的sqlite表

private static final String TABLE_CREATE = "CREATE TABLE " + TABLE_NAME + " (ID INTEGER, DEVICEID TEXT, LTIME INTEGER, LATITUDE REAL,"+
        "LONGITUDE REAL, THEPICTURE BLOB, SENT INTEGER, NOTES TEXT, COMMAND TEXT, PARAMS TEXT);";

我正在尝试插入COMMAND和PARAMS。我的sqlite代码看起来像这样

public int InsertList(String COMMAND, String info){

        try {

            JSONObject reader = new JSONObject(info);
            String param_str = reader.getString("info");

            if (_Db == null)
                _Db = getWritableDatabase();

            if (_LastId == -1)
            {
                Cursor c = _Db.query(TABLE_NAME, new String[] {"max(ID)"}, null, null, null, null, COMMAND, param_str);
                if (c != null && c.moveToFirst()) {
                    _LastId = c.getInt(0);
                    c.close();
                }
                else
                    _LastId = 0;
                c.close();
            }

            try {

                ContentValues cv = new ContentValues();
                cv.put("ID",++_LastId);

                cv.put("COMMAND",String.valueOf(COMMAND));
                cv.put("PARAMS",PARAMS);          

                _Db.insert(TABLE_NAME, "", cv);
            } catch (Exception e){
                Log.d("Log2","Error:"+e.getMessage());
            }          

        } catch (JSONException e1) {            
            Log.d("Log2","Error:"+e1.getMessage());
        }

         return _LastId;

 }

基本上是我从addList函数

获得的异常

adding Exception : Exception invalid LIMIT clauses

如何考虑将json对象插入sqlite

Answer 1

这些是query()方法的参数：

using System.Net;

string requestUri = "http:\\example.com";
using (var webClient = new WebClient()) {
    webClient.Headers[HttpRequestHeader.Accept] = "application/json";
    string json = webClient.DownloadString(requestUri);
}

Cursor c = _Db.query( TABLE_NAME, // table new String[] {"max(ID)"}, // columns null, // selection null, // selectionArgs null, // groupBy null, // having COMMAND, // orderBy param_str); // limit和orderBy参数没有意义。要查找整个表中的最大ID，这些参数必须为limit。

无论如何，有一个helper function使得从数据库中读取单个数字变得更加容易，而不必使用游标：

null

如果您已将long lastID = DatabaseUtils.longForQuery(_Db, "SELECT max(ID) FROM "+TABLE_NAME, null);列声明为ID，则会自动增量，您无需手动设置。

例外无效限制条款 - Android

1 个答案: