A summary query that uses the COUNT, AVG, and SUM functions : AVG « Aggregate Functions « SQL Server / T-SQL Tutorial

1. SQL Server / T-SQL Tutorial
2. Aggregate Functions
3. AVG

3>
4> create table Billings (
5>     BankerID           INTEGER,
6>     BillingNumber      INTEGER,
7>     BillingDate        datetime,
8>     BillingTotal       INTEGER,
9>     TermsID            INTEGER,
10>     BillingDueDate     datetime ,
11>     PaymentTotal       INTEGER,
12>     CreditTotal        INTEGER
13>
14> );
15> GO
1>
2> INSERT INTO Billings VALUES (1, 1, '2005-01-22', 165, 1,'2005-04-22',123,321);
3> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (2, 2, '2001-02-21', 165, 1,'2002-02-22',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (3, 3, '2003-05-02', 165, 1,'2005-04-12',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (4, 4, '1999-03-12', 165, 1,'2005-04-18',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (5, 5, '2000-04-23', 165, 1,'2005-04-17',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (6, 6, '2001-06-14', 165, 1,'2005-04-18',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (7, 7, '2002-07-15', 165, 1,'2005-04-19',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (8, 8, '2003-08-16', 165, 1,'2005-04-20',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (9, 9, '2004-09-17', 165, 1,'2005-04-21',123,321);
2> GO

(1 rows affected)
1> INSERT INTO Billings VALUES (0, 0, '2005-10-18', 165, 1,'2005-04-22',123,321);
2> GO

(1 rows affected)
1>
2>
3> SELECT 'After 1/1/2002' AS SelectionDate, COUNT(*) AS NumberOfBillings,
4>     AVG(BillingTotal) AS AverageBillingAmount,
5>     SUM(BillingTotal) AS TotalBillingAmount
6> FROM Billings
7> WHERE BillingDate > '2002-01-01'
8> GO
SelectionDate  NumberOfBillings AverageBillingAmount TotalBillingAmount
-------------- ---------------- -------------------- ------------------
After 1/1/2002                6                  165                990

(1 rows affected)
1>
2> drop table Billings;
3> GO