what is @ in sql code example

Example 1: what is in operator in sql

(IN) operator in sql like "OR" operator
For example: 
Select * From employees
Where department_id "IN" (60,90);

Example 2: what is in condition in sql

IN condition allows you to easily test
if an expression matches any value in a list of values.
It is for reducing  multiple OR
conditions in a SELECT, INSERT,
UPDATE, or DELETE statement.