SUM aggregate function

DECLARE @Customer AS TABLE (Customerid INT, CustomerName VARCHAR(15))
DECLARE @Project AS TABLE (Customerid INT, DocStatus INT)

INSERT INTO @Customer
VALUES
(1,'Customer1'),(2,'Customer2'),(3,'Customer3'),(4,'Customer4'),(5,'Customer5'),
(6,'Customer6'),(7,'Customer7'),(8,'Customer8'),(9,'Customer9'),(10,'Customer10'),
(11,'Customer11'),(12,'Customer12'),(13,'Customer13'),(14,'Customer14')

INSERT INTO @Project
VALUES
(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),
(8,1),(9,2),(10,3),(11,4),(12,5),(13,6),(14,7),
(1,2),(2,3),(3,4),(4,5),(5,6),(6,7),(7,1),
(8,2),(9,3),(10,4),(11,5),(12,6),(13,7),(14,1)

SELECT P.DocStatus, C.CustomerName, P.CustomerID
FROM   @Project P
       INNER JOIN @Customer C
            ON  P.CustomerID = C.CustomerID
UNION ALL
SELECT 8 AS Docstatus, c.CustomerName, COUNT(*)
FROM   @Project P
       INNER JOIN @Customer C
            ON  P.CustomerID = C.CustomerID
GROUP BY
       C.Customerid, c.CustomerName




SELECT CustomerName, [0] AS Pending, [1] AS Save_As_Draft, [2] AS Spec_Confirmed, [3] AS
       Request_Revision, [4] AS Withdraw, [5] AS Pending_RND, [6] AS Pending_QC, [7] AS
       Manday_Confirmed,[8] AS Total
FROM   (
        SELECT P.DocStatus, C.CustomerName, P.CustomerID, 1 AS customercount
        FROM   @Project P
               INNER JOIN @Customer C
                    ON  P.CustomerID = C.CustomerID
        UNION ALL
        select 8 AS Docstatus, c.CustomerName,c.Customerid, COUNT (p.Customerid)
        FROM  @Project P
               INNER JOIN @Customer C
                    ON  P.CustomerID = C.CustomerID
        GROUP BY C.Customerid, c.CustomerName
       ) p

       PIVOT(
        SUM(customercount)  FOR DocStatus IN ([0], [1], [2], [3], [4], [5], [6], [7],[8])
       ) AS pvt;
/* below is my solution see it is read the source only once  hope this one is better readable than the pivot and have a better performance too*/
SELECT C.CustomerName,
       SUM(CASE WHEN docStatus =0 THEN 1 ELSE 0 END) AS Pending,
       SUM(CASE WHEN docStatus =1 THEN 1 ELSE 0 END) AS Save_As_Draft,
       SUM(CASE WHEN docStatus =2 THEN 1 ELSE 0 END) AS Spec_Confirmed,
       SUM(CASE WHEN docStatus =3 THEN 1 ELSE 0 END) AS Request_Revision,
       SUM(CASE WHEN docStatus =4 THEN 1 ELSE 0 END) AS Withdraw,
       SUM(CASE WHEN docStatus =5 THEN 1 ELSE 0 END) AS Pending_RND,
       SUM(CASE WHEN docStatus =6 THEN 1 ELSE 0 END) AS Pending_QC,
       SUM(CASE WHEN docStatus =7 THEN 1 ELSE 0 END) AS Manday_Confirmed,
       SUM(1) AS Total
FROM   @Project P
       INNER JOIN @Customer C
            ON  P.CustomerID = C.CustomerID
GROUP BY c.CustomerName

SELECT CustomerName,[0] as Pending, [1] as Save_As_Draft, [2] as Spec_Confirmed, [3] as Request_Revision, [4] as Withdraw, [5] as Pending_RND, [6] as Pending_QC, [7] as Manday_Confirmed, [0]+[1]+[2]+[3]+[4]+[5]+[6]+[7] as Total
FROM
(
    SELECT P.DocStatus,C.CustomerName,P.CustomerID
    FROM dbo.CRF_Project P
    INNER JOIN dbo.CustomerList C
    ON P.CustomerID = C.CustomerID
) p

PIVOT
(
    COUNT (CustomerID) FOR DocStatus IN ([0], [1], [2], [3], [4], [5], [6], [7])

) AS pvt;