_ID column in Contacts database

Question

I read that the different entries in different tables are linked via the _ID column in that table. For example a contact might have an _ID = 1 I get via

ContactsContract.Contacts._ID

and now I want to read the phone number of that contact using

Cursor phoneCursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.CONTACT_ID + " = " + contactId , null, null); 
//...
String number = phoneCursor.getString(phoneCursor.getColumnIndexOrThrow(ContactsContract.CommonDataKinds.Phone.NUMBER));
String id = phoneCursor.getString(phoneCursor.getColumnIndexOrThrow(ContactsContract.CommonDataKinds.Phone._ID));

This works fine, but what I would expect is that if the _ID of the contact is 1 that the _ID of the phone number is as well one since they belong together, but they are not equal. So the question is how does Android match these entries?

Thanks, A.

Answer 1

you could get more details when you see the database tables

as far as my understanding goes this is the information I got from viewing android contacts2.db file using sqlite3 db browser

I created some 6 contacts for testing my android contacts

in contacts table the _id and raw_contact_id is actually same (it means that ContactsContract.Contacts provider )

in data table we get the real details of the person like phone number and email and firstname and last name using mimetype Id as the where condition

when considering data table use raw_contact_id as the where condition to get a particular records of the contact

ex my raw_contact_id is 1

I got 3 rows which consists of email, phone and display name in data1 column

you may ask that what if we want only phone or email or display name ....there you will need the mimetype_id as the where condition

to get phonenumber mimetype_id is 5 to get display_name mimetype_id is 6 to get email mimetype_id is 1

you may not understand all these stuff if you are a beginner ...but once if u see the internal tables u get every thing which I told you

access contact details only by contact_id or raw_contact_id and not by _id which is in every table ..that column is for different purpose ..

you can have a look at what Im saying in this image http://img94.imageshack.us/i/tablesxa.jpg

Answer 2

A contact corresponds to 1 or more raw contacts. The actual data for the contact is stored as

ContactsContract.Contacts.Data

Each data item contains the id of the raw contact it belongs to. Each raw contact contains the id of the contact it belongs to.

So, given a Contact id you can find what raw contacts it represents. Get the raw contact ids and then find what data is within this contact.