Question

出于某种原因，当我尝试插入多个数据时，我会得到每行4个重复项。我尝试了cv.clear（），我也尝试了cv = new ContentValues（），但我不知道是什么导致它插入4次。 for循环当然只运行两次，它调用db.insert两次。但我认为这与我看不到的ContentValues有关。

在MainActivity.java中

DBAdapter db = new DBAdapter(this);
db.open();    

String[] skuArray = { "1234", "4569" };
String[] nameArray = { "Something", "Anything" };
String[] descriptionArray = { "It is something", "It is anything" };
String[] costArray = { "$5.00", "$10.00"};
for (int i = 0; i < skuArray.length; i++) {
    String sku = skuArray[i];
    String name = nameArray[i];
    String description = descriptionArray[i];
    String cost = costArray[i];     
    db.insert(sku, name, description, cost;
}

在DBAdapter.java中插入（）方法

public void insert(String sku, String name, String description, String cost) {
    try {
        ContentValues cv = new ContentValues();

        // Insert into ITEM_TABLE
        cv.put(ITEM_SKU, sku);
        cv.put(ITEM_NAME, name);
        cv.put(ITEM_DESCRIPTION, description);
        db.insert(ITEM_TABLE, null, cv);

        // Insert into PRICE_TABLE
        cv = new ContentValues();
        cv.put(PRICE_SKU, sku);
        cv.put(PRICE_COST, cost);
        db.insert(PRICE_TABLE, null, cv);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

DBAdapter.java loadAllItemsQuery（）方法

public void loadAllItemsQuery() {
    try {
        String SELECT_ITEM_QUERY = "SELECT " + ITEM_SKU + ", " + ITEM_NAME + ", " + ITEM_DESCRIPTION + ", " + PRICE_COST + " FROM " + ITEM_TABLE + " INNER JOIN " + PRICE_TABLE;

        Cursor cursor = db.rawQuery(SELECT_ITEM_QUERY, null);
        cursor.moveToFirst();

        do {
            skuArray[cursor.getPosition()] = cursor.getString(0);
            nameArray[cursor.getPosition()] = cursor.getString(1);
            descriptionArray[cursor.getPosition()] = cursor.getString(2);
            priceArray[cursor.getPosition()] = cursor.getString(3);

            Log.d("loadAllItemsQuery()", "Count row: " + cursor.getCount());
            Log.d("loadAllItemsQuery()", "Current row position: " +  cursor.getPosition());
            Log.d("loadAllItemsQuery()", skuArray[cursor.getPosition()]);
        } while (cursor.moveToNext()); 

        cursor.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

结果：

Count row: 8
Current row position: 0
sku: 1234
Count row: 8
Current row position: 1
sku: 1234
Count row: 8
Current row position: 2
sku: 1234
Count row: 8
Current row position: 3
sku: 1234
Count row: 8
Current row position: 4
sku: 4569
Count row: 8
Current row position: 5
sku: 4569
Count row: 8
Current row position: 6
sku: 4569
Count row: 8
Current row position: 7
sku: 4569

Answer 1

问题可能与您的加入有关，导致它每次返回4次。

试试这个：

String SELECT_ITEM_QUERY = "SELECT DISTINCT " + ITEM_SKU + ", " + ITEM_NAME + ", " + ITEM_DESCRIPTION + ", " + PRICE_COST + " FROM " + ITEM_TABLE + " INNER JOIN " + PRICE_TABLE;

更好的选择：查看查询并更恰当地构建它，而不是选择distinct。还尝试打印所有阵列。如果其他字段中的值存在差异，您仍然会继续获得超过预期的行数。 AND 检查您的数据是否合理。查询可能是正确的，但数据也可能导致问题。

Android - 内容值重复插入4次

1 个答案: