I have a requirement where i need to save the contacts of the user and i have the following issues.
I have a user table where i would save the "user1" and i also the save the users in his contact in the same table.
And say another user "user2" has to be saved along with his contacts in user table. Consider "user2" has few contacts same as "user1"(i.e., the contact number is same but the naming is different). And i should not repeat the user who is already present. In this case i can check with contact number so if that contact number is already present i can skip saving the contact and use that id instead.
But another situation is, consider "user1" has saved his contact as "9999444494" and "user2" also has "9999444494" but they both belongs to different country say "country code +91 and +92 respectively" but it looks as if the contacts were same if they do not specify the country code and how could i get these differentiations and save it in the table.
I am stuck with this issue. Please help me. Thanks in advance.
There is no reason to assume that just because two people have the same phone number, that they will change that phone number at the same time.
Say your two users are employees of the same company and they give the main switchboard number as their contact number. When one quits the company their contact info will change but the other will stay the same. The same could happen if your users are members of a family who share a phone. When one leaves (child moves out, parents divorce,...) the contact numbers for each user will be different.
Therefore: don't try to rationalize contact numbers down to a single record. Repeated entries are not the same as duplicate entries when that repetition is coincidental.
Regarding country code, you need to include that in your contact information in either the same column or a separate column. If that country code is nullable then keeping it separately might be helpful so that you can see plainly that the information is missing.