安卓：在ContentResolver的独特和GROUPBY [英] Android: Distinct and GroupBy in ContentResolver

问题描述

什么将是一个明智的方式来增加 DISTINCT 和/或 GROUPBY 到 ContentResolver的 - 基于查询。现在，我要创建自定义的URI为每个特殊情况。有没有更好的办法？ （我还计划1.5的最小公分母）

What would be a sensible way to add DISTINCT and/or GROUPBY to ContentResolver- based queries. Right now I have to create custom URI for each special case. Is there a better way? (I still program for 1.5 as lowest common denominator)

推荐答案

由于没有人来回答，我只是要告诉我怎么解决这一点。基本上，我会创建自定义的URI为每种情况，并通过在选择参数的标准。然后的ContentProvider＃查询里面我会查明案情，并根据表名，选择参数构造原始查询。

Since no one came to answer I'm just going to tell how I solved this. Basically I would create custom URI for each case and pass the criteria in selection parameter. Then inside ContentProvider#query I would identify the case and construct raw query based on table name and selection parameter.

下面是简单的例子：

switch (URI_MATCHER.match(uri)) {
    case TYPES:
        table = TYPES_TABLE;
        break;
    case TYPES_DISTINCT:
        return db.rawQuery("SELECT DISTINCT type FROM types", null);
    default:
        throw new IllegalArgumentException("Unknown URI " + uri);
    }
    return db.query(table, null, selection, selectionArgs, null, null, null);

这篇关于安卓：在ContentResolver的独特和GROUPBY的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！