Android SQLite查詢返回null

Question

我在Android中有一個靜態的sqlite數據庫。 函數采用int類型的輸入，並查詢數據庫。 它可以正常工作，直到輸入值為97,500，但是如果我輸入更大的值，則會發生以下兩種情況之一

1. 如果輸入為98,000-99,500，則返回null
2. 如果輸入大於100,000，則返回錯誤數據

這是發生故障的功能：

    Budget getBudget(int income,String name)
{
    Budget B=null;
    Log.d("DB", String.valueOf(income));
    try{
        SQLiteDatabase db=this.getReadableDatabase();
        Cursor cur=db.rawQuery("SELECT * FROM "+BudgetTable+" WHERE "+Low+"<=? AND "+High+">=?", new String[]{String.valueOf(income),String.valueOf(income)});
        Log.d("DB", String.valueOf(cur.getCount()));
        if(cur.getCount()!=0)
        {
            Log.d("DB", "Cursor not empty");
            cur.moveToFirst();
            B=new Budget(0, income,cur.getInt(cur.getColumnIndex(MortgageRent)),cur.getInt(cur.getColumnIndex(Utilities)) , 
                    cur.getInt(cur.getColumnIndex(LightnPower)), cur.getInt(cur.getColumnIndex(PhonenInternet)), 
                    cur.getInt(cur.getColumnIndex(HomeMaintenance)), cur.getInt(cur.getColumnIndex(HomeCleaning)), 
                    cur.getInt(cur.getColumnIndex(Groceries)), cur.getInt(cur.getColumnIndex(Clothing)),0, 
                    cur.getInt(cur.getColumnIndex(PersonalGrooming)), cur.getInt(cur.getColumnIndex(MedicalnPharmacy)), 
                    cur.getInt(cur.getColumnIndex(HealthInsurance)), cur.getInt(cur.getColumnIndex(LifeInsurance)), 
                    cur.getInt(cur.getColumnIndex(HomeInsurance)), cur.getInt(cur.getColumnIndex(Accounting)), 
                    cur.getInt(cur.getColumnIndex(BankFees)), cur.getInt(cur.getColumnIndex(Fuel)), 
                    cur.getInt(cur.getColumnIndex(ServicenRepairs)), cur.getInt(cur.getColumnIndex(GovernmentCharges)), 
                    cur.getInt(cur.getColumnIndex(CarInsurance)),0, cur.getInt(cur.getColumnIndex(PublicTransport)), 
                    cur.getInt(cur.getColumnIndex(Entertainment)), cur.getInt(cur.getColumnIndex(SportsnGym)),
                    cur.getInt(cur.getColumnIndex(EatOut)), cur.getInt(cur.getColumnIndex(Alcohol)), 
                    cur.getInt(cur.getColumnIndex(Gifts)), cur.getInt(cur.getColumnIndex(Holidays)), 
                    cur.getInt(cur.getColumnIndex(NewspapernMagazine)), cur.getInt(cur.getColumnIndex(Others)), 0, 0, name);

            Log.d("DB", String.valueOf(cur.getInt(cur.getColumnIndex(IncomeLevel))));
            cur.close();
            db.close();

        }
    }catch(Exception ex)
    {
        Log.d("DB", ex.getMessage());
    }
    return B;
}

下面是數據庫中數據的屏幕截圖...我不知道為什么它不起作用。

Answer 1

由於看不到您的數據庫，因此我被認為是您的問題的根源是：

Cursor cur=db.rawQuery("SELECT * FROM "+BudgetTable+" WHERE "+Low+"<=? AND "+High+">=?", new String[]{String.valueOf(income),String.valueOf(income)});

特別是您同時使用income大於等於和小於等於這兩個事實。 您確定這就是您想要的嗎？ 你確定這不是冒充

Cursor cur=db.rawQuery("SELECT * FROM "+BudgetTable+" WHERE "+Low+"<=? AND "+High+">=?", new String[]{String.valueOf(lowIncome),String.valueOf(highIncome)});

Answer 2

您不應該將數字作為字符串傳遞，因為字符串具有不同的比較規則，例如，字符串“ 2000”將被視為大於字符串“ 102500”。

他們在javadoc文檔中對此進行了警告：

selectionArgs您可以在查詢的where子句中包含？s，它將替換為selectionArgs中的值。 這些值將綁定為字符串。

您應該這樣重寫查詢：

Cursor cur=db.rawQuery("SELECT * FROM "+BudgetTable+
                      " WHERE "+Low+"<=" + income + " AND "+High+">=" + income);

同樣，這是一個很常見的問題，有些人遇到了類似的問題： SQLite rawQuery selectionArgs和Integers Fields