带有 WHERE、AND、OR 子句的 Android Sqlite 搜索查询答案

【问题标题】：Android Sqlite search query with WHERE,AND, OR clauses带有 WHERE、AND、OR 子句的 Android Sqlite 搜索查询
【发布时间】：2018-05-18 16:34:17
【问题描述】：

在这里，我需要从表'TABLE_NAME' 中获取结果，其中'COLUMN_NAME_COUNTRY' = country 'AND' 'COLUMN_NAME_CATEGORY' = local 'OR' NA (Na also a value in the 'COLUMN_NAME_CATEGORY'。以下是我的代码：

public List<AppDataBean>getAllDataForSelectedCountryWithCategory(String country){

        ArrayList<AppDataBean>dataList= new ArrayList<>();
        SQLiteDatabase db = AppDbHelper.getInstance(context).getWritableDatabase();
        dataList.clear();

        try {
            Cursor c = db.rawQuery("SELECT * FROM " + AppDbConstructor.AppData.TABLE_NAME + " WHERE " + AppDbConstructor.AppData.COLUMN_NAME_COUNTRY + "='" + country + "'"
                    + " AND " + AppDbConstructor.AppData.COLUMN_NAME_CATEGORY + "='" + "Local" + "'" + " OR " + AppDbConstructor.AppData.COLUMN_NAME_CATEGORY + "='" + "NA" + "'" , null);

            if (c.getCount()>0)
            {
                if (c.moveToFirst())
                {
                    for (int i=0; i<c.getCount(); i++)
                    {
                        AppDataBean appDataBean = new AppDataBean();
                        appDataBean.setCategory(c.getString(c.getColumnIndex(AppDbConstructor.AppData.COLUMN_NAME_CATEGORY)));
                        appDataBean.setUrl(c.getString(c.getColumnIndex(AppDbConstructor.AppData.COLUMN_NAME_URL)));
                        appDataBean.setSource(c.getString(c.getColumnIndex(AppDbConstructor.AppData.COLUMN_NAME_SOURCE)));
                        appDataBean.setIconUrl(c.getString(c.getColumnIndex(AppDbConstructor.AppData.COLUMN_NAME_ICON_URL)));
                        appDataBean.setCountry(c.getString(c.getColumnIndex(AppDbConstructor.AppData.COLUMN_NAME_COUNTRY)));
                        Log.d("APP_DB_SOURCE","COLUMN_NAME_SOURCE: "+ c.getString(c.getColumnIndex(AppDbConstructor.AppData.COLUMN_NAME_URL))
                                + ", " + c.getString(c.getColumnIndex(AppDbConstructor.AppData.COLUMN_NAME_CATEGORY)));

                        dataList.add(appDataBean);
                        Log.d("APPDBSOURCE", "LIST_VALUES_ARE" + dataList.get(i).getCategory() + ", " + dataList.get(i).getCountry());
                        c.moveToNext();
                    }
                }
            }
            c.close();
        }catch (Exception e){
            e.printStackTrace();
        }
        finally
        {
            db.close();
        }

        return dataList;
    }

最终结果是“所有国家/地区”和“本地”类别。

【问题讨论】：

你遇到了什么问题？
可能您的所有国家都被标记为本地/NA。
你少了一个括号，因为AND 和OR 的优先级不是你想的那样。大多数人都弄错了，所以最好在混合AND 和OR 时总是使用括号。你写了WHERE country = '...' AND category = 'Local' OR category = 'NA'，意思是WHERE (country = '...' AND category = 'Local') OR category = 'NA'，但你的意思是WHERE country = '...' AND (category = 'Local' OR category = 'NA')。更好的是，使用IN 子句：WHERE country = '...' AND category IN ('Local', 'NA')
非常感谢。它正在工作

标签： java android android-sqlite android-cursor android-query

【解决方案1】：

你缺少括号。

您可以这样做：

Cursor c = db.rawQuery("SELECT * FROM " + AppDbConstructor.AppData.TABLE_NAME + " WHERE " + AppDbConstructor.AppData.COLUMN_NAME_COUNTRY + "='" + country + "'"
                    + " AND (" + AppDbConstructor.AppData.COLUMN_NAME_CATEGORY + "='" + "Local" + "'" + " OR " + AppDbConstructor.AppData.COLUMN_NAME_CATEGORY + "='" + "NA" + "')" , null);

或者像这样：

Cursor c = db.rawQuery("SELECT * FROM " + AppDbConstructor.AppData.TABLE_NAME + " WHERE " + AppDbConstructor.AppData.COLUMN_NAME_COUNTRY + "='" + country + "'"
                    + " AND " + AppDbConstructor.AppData.COLUMN_NAME_CATEGORY + " IN " + "('"+ "Local"+"','"+"NA" + "')" , null);

【讨论】：