Declare « Transact SQL « SQL Server / T-SQL Tutorial

20.1.1.The DECLARE statement has a pretty simple syntax:
20.1.2.It is possible to define several variables in a single Declare statement.
20.1.3.The names of variables must begin with @
20.1.4.Simple SELECT query written using variables for field names.
20.1.5.Declare a table type variable and query it
20.1.6.DECLARE @Out Int (get value out of a procedure)
20.1.7.DECLARE @Out Int