Common Table Expression, why semicolon?

Question

Usually in SQL Server Common Table Expression clause there is semicolon in front of the statement, like this:

;WITH OrderedOrders AS --semicolon here (     SELECT SalesOrderID, OrderDate,     ROW_NUMBER() OVER (ORDER BY OrderDate) AS 'RowNumber'     FROM Sales.SalesOrderHeader  )  SELECT *  FROM OrderedOrders  WHERE RowNumber BETWEEN 50 AND 60 

Why?

Answer 1

• To avoid ambiguity because WITH can be used elsewhere
  ..FROM..WITH (NOLOCK)..
RESTORE..WITH MOVE..
• It's optional to terminate statements with ; in SQL Server

Put together, the previous statement must be terminated before a WITH/CTE. To avoid errors, most folk use ;WITH because we don't know what is before the CTE

So

DECLARE @foo int;  WITH OrderedOrders AS (     SELECT SalesOrderID, OrderDate, ...; 

is the same as

DECLARE @foo int  ;WITH OrderedOrders AS (     SELECT SalesOrderID, OrderDate, ...; 

The MERGE command has a similar requirement.