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    <p>The <code>Uri</code> does not point to any table. It points to whatever you feel like pointing it to.</p> <p>Let's pretend that your two tables are <code>Customer</code> and <code>Order</code>. One customer may have many orders. You want to execute a query to get all outstanding orders... but you want to join in some customer-related columns that you will need, such as the customer's name.</p> <p>Let's further pretend that you already have <code>content://your.authority.goes.here/customer</code> and <code>content://your.authority.goes.here/order</code> defined to purely query those tables.</p> <p>You have two choices:</p> <ol> <li><p>Add the join of the customer's display name on your <code>/order</code> <code>Uri</code>. Having another available column probably will not break any existing consumers of the provider (though testing is always a good idea). This is what <code>ContactsContract</code> does -- it joins in some base columns, like the contact's name, on pretty much all queries of all tables.</p></li> <li><p>Create <code>content://your.authority.goes.here/orderWithCust</code> that does the same basic query as <code>/order</code> does, but contains your join. In this case, you could have <code>insert()</code>, <code>update()</code>, and <code>delete()</code> throw some sort of <code>RuntimeException</code>, to remind you that you should not be modifying data using <code>/orderWithCust</code> as a <code>Uri</code>.</p></li> </ol> <p>In the end, designing a <code>ContentProvider</code> <code>Uri</code> system is similar to designing a REST Web service's URL system. In both cases, the join has to be done on the provider/server side, and so you may need to break the one-table-to-one-URL baseline to offer up some useful joins.</p>
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    1. COI read your answer above but in my case whole point of using join is to retrieve columns from multiple related table with just one query. inside a single cursor that i get from cursor loader i need DISPLAY_NAME_PRIMARY from ContactsContract.Contact table ,ACCOUNT_NAME from ContactsContract.RawContact table and DATA1 from ContactsContract.DATA table.Now i dont understand how single Uri can help me with this because if i give Uri pointing to ContactsContract.RawContact table then how will i access related columns of ContactsContract.Contact and ContactsContract.Data table
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      1. USAbhishek Chauhan
    2. CO@AbhishekChauhan: Well, in your case, you did not write the `ContentProvider`, which means that you cannot "hack it up somehow with rawSql inside content provider", as you claimed in your question. My answer is aimed at somebody who is writing the `ContentProvider` and therefore can do the join inside of it. In your case, you will have to manually "join" your data yourself from multiple `Cursor` objects, and the `Loader` framework will not help much in this area. Off the cuff, I'd use an `AsyncTask`, then do queries using `ContentResolver` and merge your data in `doInBackground()`, I guess.
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    3. COya ... thanks i will use asynctask for it and merge later...this one will suit me better
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