How to solve Php 7 not found Sqlite3? [closed]

Question

I upgraded my Ubuntu to 16.04 LTS. I had php5 on that OS. I used Sqlite3 in one script and I could run it from cli easily.

No after upgrade it is php7 which runs for cli => /etc/php/7.0/cli

But it cannot detect the SQLite3, and I get 'PHP Fatal error: Class 'SQLite3' not found' error.

I tried to install it again with this command:

sudo apt-get install sqlite3

But it says it is installed now.

How can I solve this problem that php7 could detect SQLite3?

Thanks in advance