Call user-defined function in where clause : function « Procedure Function « SQL Server / T-SQL Tutorial

4> CREATE TABLE titles(
5>    title_id       varchar(20),
6>    title          varchar(80)       NOT NULL,
7>    type           char(12)          NOT NULL,
8>    pub_id         char(4)               NULL,
9>    price          money                 NULL,
10>    advance        money                 NULL,
11>    royalty        int                   NULL,
12>    ytd_sales      int                   NULL,
13>    notes          varchar(200)          NULL,
14>    pubdate        datetime          NOT NULL
15> )
16> GO
1>
2> insert titles values ('1', 'Secrets',   'popular_comp', '1389', $20.00, $8000.00, 10, 4095,'Note 1','06/12/94')
3> insert titles values ('2', 'The',       'business',     '1389', $19.99, $5000.00, 10, 4095,'Note 2','06/12/91')
4> insert titles values ('3', 'Emotional', 'psychology',   '0736', $7.99,  $4000.00, 10, 3336,'Note 3','06/12/91')
5> insert titles values ('4', 'Prolonged', 'psychology',   '0736', $19.99, $2000.00, 10, 4072,'Note 4','06/12/91')
6> insert titles values ('5', 'With',      'business',     '1389', $11.95, $5000.00, 10, 3876,'Note 5','06/09/91')
7> insert titles values ('6', 'Valley',    'mod_cook',     '0877', $19.99, $0.00,    12, 2032,'Note 6','06/09/91')
8> insert titles values ('7', 'Any?',      'trad_cook',    '0877', $14.99, $8000.00, 10, 4095,'Note 7','06/12/91')
9> insert titles values ('8', 'Fifty',     'trad_cook',    '0877', $11.95, $4000.00, 14, 1509,'Note 8','06/12/91')
10> GO

3> CREATE FUNCTION AveragePrice(@booktype varchar(12))
4> RETURNS money
5> AS
6> BEGIN
7>     DECLARE @avg money
8>     SELECT @avg = avg(price)
9>     FROM titles
10>     WHERE type = @booktype
11>
12>     RETURN @avg
13> END
14> GO
1>
2> SELECT title_id, price
3> FROM titles
4> WHERE price > dbo.AveragePrice('business')
5> AND type = 'business'
6> GO
title_id             price
-------------------- ---------------------
2                                  19.9900
1>
2> DECLARE @avg money
3> EXEC @avg = dbo.AveragePrice 'business'
4> SELECT @avg
5> GO

---------------------
              15.9700
1>
2>
3> drop FUNCTION AveragePrice;
4> GO
1>
2> drop table titles;
3> GO
1>

21.2.function
	21.2.1.	The syntax for creating a multi-statement table-valued function
	21.2.2.	The syntax for creating a scalar-valued function
	21.2.3.	The syntax for creating a simple table-valued function
	21.2.4.	The syntax of the ALTER FUNCTION statement for a scalar valued function
	21.2.5.	The syntax for altering a simple table-valued function
	21.2.6.	The syntax for altering a multi-statement table-valued function
	21.2.7.	Call user-defined function in where clause
	21.2.8.	Call two user-defined functions in a select statement
	21.2.9.	Function WITH SCHEMABINDING
	21.2.10.	Multistatement Table-Valued Functions
	21.2.11.	Pass a declared variable to a function
	21.2.12.	Return TOP 100 PERCENT WITH TIES from a function
	21.2.13.	Get the 3 employees with the most RegionPlace
	21.2.14.	Use function as a view
	21.2.15.	Create a scalar-valued function that returns the total Billing amount due
	21.2.16.	Invoke the scalar-valued function
	21.2.17.	A SELECT statement that uses the function in a join operation
	21.2.18.	Use function to wrap a long sql statement
	21.2.19.	Query a table returned from a function