Infosys interview question

1st question self And programs like swaping two numbers with out using 3rd variables and reverse a string without using built-in function and merge sort and 2nd largest element in array and Buble sort. And he asked me which programming language you more comfortable i said Java he asked what difference between local variable and global variable.and all oops concepts and asked SQL questions like different between delete and trancate and Clint server architecture he touched all DBMS and os and computer networking concept.