How to make Subscribe and give notifications to who the one subscribe on Android Application?

i already tried search how to this but i didn't found it.

So, this is my story and my question.

i have and android application which is the app has user & channel (This is an online app, i'm using xampp to be my server and i'm using .php to retrieve and send data), got it ?

So, every user on there can make a channel, for example create channel about Gym, Fashion or something like that and the users can give more than one information to the channel(i'm using listview to show in the app).

Here is the idea, i want the user can follow to other channel or public channel, so when they are decided to follow the channel, they can receive notifications everytime the channel have a new information(information added from owner of the channel), the problem is, how to do this ?

I tried to make a table isFollow contains user, channel and isFollow(Y/N), but let say if i got the data like this :

• Bert Gym Y
• David Gym Y

Then, what should i do to the data ?

Please help me if someone know the solution to do this, thankyou so much!

Best regards, Vian.