sql - Different ways to alias a column

Question

What is the difference between

select  empName as EmployeeName from employees

versus

select  EmployeeName = empName from employees

from a technical point of view. Not sure if this is just SQL server specific or not.

Appreciate your answers.

Answer 1

I'd prefer the first one, since the second one is not portable -

select  EmployeeName = empName from employees

is either a syntax error (at least in SQLite and Oracle), or it might not give you what you expect (comparing two columns EmployeeName and empName and returning the comparison result as a boolean/integer), whereas

select  empName EmployeeName from employees

is the same as

  select  empName as EmployeeName from employees

which is my preferred variant.