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我有一个棘手的问题。我的应用程序将用户数据输入到 SQLite 数据库中，并且我已经设法编写查询以取回数据。

这包括获取不同值列表的查询，示例如下。假设您有以下数据：

Column a  |  Column b  | Column c
   a            a           a
   a            b           b
   a            b           b
   b            b           b

使用“分组依据”功能，查询将创建以下列表：

aaa
abb
bbb

所以我正在尝试，但未能做的是扩展它并计算每个不同条目出现的次数 - 所以在上述情况下，它看起来像这样：

1 x aaa
2 x abb
1 x bbb

那么有没有一种方法，一旦你查询了数据库，就可以从光标中获取每个不同条目的出现次数 - 或者我是否需要编写一个单独的查询来获取这些信息..

这是我目前的查询：

public Cursor fetchDamagedComponentSpecForInspection(long inspectionId, String componentType) {
    Cursor mCursor = rmDb.query(true, DAMAGED_COMPONENTS_TABLE, new String[] {
            DAMAGED_COMPONENT_ID,
            LOCATION_LINK,
            RUN_LINK,
            AREA_LINK,
            INSPECTION_LINK,
            LOCATION_REF,
            RACKING_SYSTEM,
            COMPONENT,
            COMPONENT_TYPE,
            QUANTITY,
            POSITION,
            RISK,
            ACTION_REQUIRED,
            NOTES_GENERAL,
            MANUFACTURER,
            TEXT1,
            TEXT2,
            TEXT3,
            TEXT4,
            NOTES_SPEC,
            SPEC_SAVED}, 
            INSPECTION_LINK + " = " + inspectionId + " AND " + COMPONENT_TYPE + " = ? AND " + SPEC_SAVED + " = ? ", 
            new String[] {componentType, "Yes"},
            MANUFACTURER + ", " + TEXT1 + ", " + TEXT2 + ", " + TEXT3 + ", " + TEXT4 + ", " + NOTES_SPEC,
            null, null, null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

有关其他信息，这是我调用查询并检索数据的主要活动中的代码：

final Cursor componentsAndSpecCursor = (Cursor) rmDbHelper.fetchComponentsAndSpecForManufacturer(inspectionId, rackingSystem, manufacturer);
                if(componentsAndSpecCursor.moveToFirst()){
                    do {
                        componentType = componentsAndSpecCursor.getString(componentsAndSpecCursor.getColumnIndex(RMDbAdapter.COMPONENT_TYPE));
                        specText1 = componentsAndSpecCursor.getString(componentsAndSpecCursor.getColumnIndex(RMDbAdapter.TEXT1));
                        specText2 = componentsAndSpecCursor.getString(componentsAndSpecCursor.getColumnIndex(RMDbAdapter.TEXT2));
                        specText3 = componentsAndSpecCursor.getString(componentsAndSpecCursor.getColumnIndex(RMDbAdapter.TEXT3));
                        specText4 = componentsAndSpecCursor.getString(componentsAndSpecCursor.getColumnIndex(RMDbAdapter.TEXT4));
                        specNotes = componentsAndSpecCursor.getString(componentsAndSpecCursor.getColumnIndex(RMDbAdapter.NOTES_SPEC));
                        message.append(componentType).append(" ").append(specText1).append(" ").append(specText2).append(" ").append(specText3).append(" ").append(specText4).append(" ").append(specNotes).append("\r\n");
                    }
                    while (componentsAndSpecCursor.moveToNext());
                }
                componentsAndSpecCursor.close();

所以我也不知道一旦我在查询中包含了这段代码（我仍然看不到它是如何完成的！），我将如何获得计数。

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3 回答 3

1

The query that you want is:

select count(*) as cnt, cola, colb, colc
from YourTable
group by cola, colb, colc

I'm not sure how to put this into your code. You don't seem to have a query that returns the combinations in the snippet of code that you provided.

于 2013-01-05T16:35:36.343 回答
1

Did u try adding COUNT(*) function to your columns list?

see this: count columns group by

于 2013-01-05T16:01:55.323 回答
0

尝试这个。

获取所有唯一值并将它们临时存储在某个地方，然后循环并执行另一个查询以尝试再次找到这些值，每次你找到一个，更新一些计数器。

于 2013-01-05T15:52:31.023 回答