Perguntas de entrevista de vagas de Database Developer da empresa AXA

I was asked many technical questions about database: e.g. 1. need to write a query to generate a output comma seperated: select empname from employee if there are 10 records, write a query in a way so that all empname (10 records) should come in one field comma seperated. 2. if a number is too large like 4.2 E+15, what should be the process and what should be the data type for this so that it will come in its proper form.