How can I do here so that my php connects with sql [duplicate]

Fatal error: Uncaught Error: Call to undefined function mysql_real escape_ string0 in C: brampplhtdocs 201806862 server php: 14 Stack trace: #O C lampp’htdocs1201806862 Registration php(1): include0 #1
(main) thrown in C:lampplhtdoes201S06S62server.php on line 14