與工會選擇所有聲明拋出異常：沒有這樣的列：借

Question

我有存儲在它的錢的項目表，按日期。
一些資金項目類型爲貸款和他人借用。

我想要做的，放在一個ListView 3個元素：日期，貸款金額爲這個日期的總和，借款金額爲這個日期的總和。

這裏是我的代碼，以填補我的光標：

Cursor cursor = mDb.rawQuery("SELECT date_o, loan, borrow FROM " + 
         "(SELECT strftime('%m', date) as date_o, SUM(amount) as loan FROM " + 
         "(SELECT date, amount FROM " + DATABASE_TABLE + " WHERE date > date('now', '-6 months') AND TYPE = " + ActivityClass.DATABASE_LOAN_TYPE + " ORDER BY date DESC) " + 
         "GROUP BY strftime('%m', date) " + 
         "UNION ALL " + 
         "SELECT strftime('%m', date) as date_o, SUM(amount) as borrow FROM " + 
         "(SELECT date, amount FROM " + DATABASE_TABLE + " WHERE date > date('now', '-6 months') AND TYPE = " + ActivityClass.DATABASE_BORROW_TYPE + " ORDER BY date DESC) " + 
         "GROUP BY strftime('%m', date)) GROUP BY date_o", null); 

這裏是代碼，以填補我的ListView：

List<List<Float>> amountByMonth = new ArrayList<>(); 
     List<Float> data = new ArrayList<>(); 

     if (cursor.moveToFirst()) { 
      do { 
       data.add(Float.parseFloat(cursor.getString(0))); 
       data.add(Float.parseFloat(cursor.getString(1))); 
       data.add(Float.parseFloat(cursor.getString(2))); 
       amountByMonth.add(data); 
      } 
      while (cursor.moveToNext()); 
     } 

所以我的函數會返回一個List<List<Float>>。

我的問題是：

Couldn't read row 0, col 2 from CursorWindow 

所以我的調查表明，cursor.getString(2)不存在（拋出異常），我認爲我的查詢被嚴重構成。

表詳細信息如下：

private static final String TABLE_MONEY = "money", 
      KEY_MONEY_ID = "id", 
      KEY_MONEY_TITLE = "title", 
      KEY_MONEY_AMOUNT = "amount", 
      KEY_MONEY_DETAILS = "details", 
      KEY_MONEY_DATE = "date", 
      KEY_MONEY_TYPE_FK_ID = "type", 
      KEY_MONEY_CONTACT_FK_ID = "contact", 
      KEY_MONEY_REMINDER_FK_ID = "reminder"; 

如果您需要進一步的細節，不要猶豫，問。

編輯：我修改我的查詢，是因爲我在測試//。 我在這裏得到的問題是列借用是未知的。

Answer 1

目前，你假裝閱讀列僅選擇時：SELECT strftime('%m', date) as date_o, SUM(amount) as loan ...

當您使用UNION條款，你必須有相同的列在所有的子查詢（loan和borrow AREN在同一列中）。
您可以使用在各自的子查詢0 AS borrow和0 AS loan假冒列佔位符的第三列。

即：

Cursor cursor = mDb.rawQuery("SELECT date_o, loan, borrow FROM " + 
    "(SELECT strftime('%m', date) as date_o, SUM(amount) as loan, 0 AS borrow FROM " + 
    "(SELECT date, amount FROM " + DATABASE_TABLE + " WHERE date > date('now', '-6 months') AND TYPE = " + ActivityClass.DATABASE_LOAN_TYPE + " ORDER BY date DESC) " + 
    "GROUP BY strftime('%m', date) " + 
    "UNION ALL " + 
    "SELECT strftime('%m', date) as date_o, 0 AS loan, SUM(amount) as borrow FROM " + 
    "(SELECT date, amount FROM " + DATABASE_TABLE + " WHERE date > date('now', '-6 months') AND TYPE = " + ActivityClass.DATABASE_BORROW_TYPE + " ORDER BY date DESC) " + 
    "GROUP BY strftime('%m', date)) GROUP BY date_o", null);