1.
php – Call to undefined method mysqli_stmt::get_result
stackoverflow.com/questions/8321096/call-to-undefined-method-mysqli-stmtget-result
2. 
PHP: mysqli_stmt::get_result – Manual
www.php.net/manual/en/mysqli-stmt.get-result.php
3.
Call to Undefined Function mysql_connect()
www.stechies.com/call-undefined-function-mysqlconnect-error-php-7/
4.
PHP MySQLi Prepared Statements Tutorial to Prevent SQL Injection
websitebeaver.com/prepared-statements-in-php-mysqli-to-prevent-sql-injection
5.
How to report errors in mysqli – Treating PHP Delusions
phpdelusions.net/mysqli/error_reporting
6.
[Solved] Fatal error: Uncaught Error: Call to a member function…
www.thewebblinders.in/programming/article/fatal-error-call-to-member-function-fetch_assoc-on-boolean-6066
7.
Dynamically Bind Params in Prepared Statements with MySQLi
www.pontikis.net/blog/dynamically-bind_param-array-mysqli
8.
PHP MySQLi Functions: mysqli_query, mysqli_connect…
www.guru99.com/mysql-php-and-other-database-access-methods.html
9. 
All About MYSQLI Prepared Statements in PHP | Supun Kavinda’s Blog
supunkavinda.blog/php/mysqli-prepared-statements
10.
Calling non-static class methods statically result in a fatal error
php.watch/versions/8.0/non-static-static-call-fatal-error
11.
What can I do to fix warning: mysqli_fetch_array… – CodeProject
www.codeproject.com/Questions/1233256/What-can-I-do-to-fix-warning-mysqli-fetch-array-ex
Conclusion
Guide above should be useful for Call To Undefined Method Mysqli_stmt::get_result().