CAST(AVG(dec1) AS dec(5,2)) : AVG « Aggregate Functions « SQL Server / T-SQL Tutorial

6> CREATE TABLE T (
7>     int1 int,
8>     bit1 bit,
9>     varchar1 varchar(3),
10>     dec1 dec(5,2),
11>     cmp1 AS (int1 + bit1)
12> )
13> GO
1>
2> INSERT T (int1, bit1) VALUES (1, 0)
3> INSERT T (int1, varchar1) VALUES (2, 'abc')
4> INSERT T (int1, dec1) VALUES (3, 5.25)
5> INSERT T (bit1, dec1) VALUES (1, 9.75)
6> GO

(1 rows affected)

(1 rows affected)

(1 rows affected)

(1 rows affected)
1> SELECT CAST(AVG(dec1) AS dec(5,2)) 'Avg of dec1'
2> FROM T
3> WHERE dec1 IS NOT NULL
4> GO
Avg of dec1
-----------
       7.50

(1 rows affected)
1> drop table t;
2> GO
1>
2>

9.2.AVG
	9.2.1.	AVG calculates the average for selected records of numeric data in a column or the average for DISTINCT (unique) values of the selected records.
	9.2.2.	Using DISTINCT in Aggregate Functions
	9.2.3.	A summary query that uses the COUNT, AVG, and SUM functions
	9.2.4.	adds the WHERE statement to calculate the average
	9.2.5.	Selecting titles that sell more than the average.
	9.2.6.	CAST(AVG(dec1) AS dec(5,2))