Question

我正在尝试从SQLite中的表的多个特定列中检索数据，但是使用下面的代码，我不确定为什么，但是不是从两个不同的列中获取数据，而是从第一列中获取数据我将其放入方法中，即“支出”表的“预算”列：-

    public Cursor getLatestAmount(String id, String category) {
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor latestamount = db.rawQuery("SELECT "+category+" FROM spendings WHERE id =" +id , null);
        return latestamount;
    }

使用上面的代码，我的“ amountfromdb_budget”和“ amountfromdb_foodndrinks”都将被插入到SQLite的“ budget”列中。我的目标是将“预算”列中的值检索到“ amountfromdb_budget”中，将“ foodndrinks”列中的值检索到“ amountfromdb_foodndrinks”中。

下面是我的DatabaseHelper类中的“ getLatestAmount”方法：-

    private static final String SPENDING_TABLE = "spendings";
    private static final String ID_SPENDING = "id";
    private static final String BUDGET = "budget";
    private static final String TOTAL_EXPENSES = "total_expenses";
    private static final String FOODNDRINKS = "foodndrinks";
    private static final String TRAVEL = "travel";
    private static final String SHOPPING = "shopping";
    private static final String ENTERTAINMENT = "entertainment";
    private static final String OTHERS = "others";
    private static final String BALANCE = "balance";

“支出”表的结构如下：-

add_filter( 'woocommerce_default_address_fields' , 'filter_default_address_fields', 20, 1 );

Answer 1

从获得食物和饮料的量起，您没有覆盖光标。因此，您仍在使用预算光标。因此，将结果从getLatestAmount保存到latestamount。

更改

myDb.getLatestAmount(id, temp_category);

至

latestamount = myDb.getLatestAmount(id, temp_category);

因此您的代码应如下所示

String temp_category = "budget";
Cursor latestamount = myDb.getLatestAmount(id, temp_category); 
if (latestamount.getCount() == 0) { 
    Toast.makeText(AddExpenses.this, "No amount found !", Toast.LENGTH_LONG).show(); 
} else {
    latestamount.moveToFirst();
    amountfromdb_budget = latestamount.getDouble(0);
} 

temp_category = "foodndrinks";
// the line below is what you needed to change
latestamount = myDb.getLatestAmount(id, temp_category); 
if (latestamount.getCount() == 0) { 
    Toast.makeText(AddExpenses.this, "No amount found !", Toast.LENGTH_LONG).show(); 
} else { 
    latestamount.moveToFirst();
    amountfromdb_foodndrinks = latestamount.getDouble(0);
}

从表SQLite的多个特定列中检索数据

1 个答案: