Question

我在Android中有一个静态sqlite数据库。函数采用int类型的输入并对数据库进行查询。输入值为97,500时工作正常，但如果我输入任何更大的值，则会发生两种情况中的一种

如果输入为98,000-99,500，则返回null
如果输入大于100,000，则返回错误的数据

这是发生故障的功能：

    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;
}

下面是数据库中数据的截图...我无法弄清楚它为什么不起作用。 Here's a screenshot of the data in database

Answer 1

由于我无法看到您的数据库，因此我认为您的问题来源就是这一行：

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

特别是你使用income来表示大于等于AND小于等于的事实。你确定这是你想要的吗？你确定它不是cuppose

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

Answer 2

您不应将数字作为字符串传递，因为字符串具有不同的比较规则，例如，字符串“2000”将被视为大于字符串“102500”。

他们在javadoc文档中警告过它：

selectionArgs您可以在查询中的where子句中包含？s，它将被selectionArgs中的值替换。这些值将绑定为字符串。

您应该像这样重写您的查询：

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

此外，这是一个非常常见的问题，有些人遇到了类似的问题：SQLite rawQuery selectionArgs and Integers Fields

Android Sqlite查询返回null

2 个答案: