My first table valued function and cursor

问题

I have this query:

SELECT name, lastname
FROM contestant 
WHERE  name= 'John'  AND lastname = 'Smith'

I get several results from the query above and I need to use them for the following query:

SELECT  name, lastname,prize, city 
FROM draw
WHERE  name= name from table contestant  AND lastname= name from table contestant

Now I’m building a table valued function with a cursor and a WHILE so I can have a table with the results.

Here’s my try, can you please help me complete it? it will be very helpful to me in order to understand this TSQL chapter. Thanks!

CREATE FUNCTION [dbo].[myFunction]
(
    @name varchar (44),
    @lastname varchar (44) 
)
RETURNS 
@tmpTable TABLE 
(   
    name char(44),
    lastname char(44),
    prize varchar(44),
    city char(44)

)
AS
BEGIN

    DECLARE 
/* what do I have to input here */

    DECLARE myCursor CURSOR FOR

SELECT name, lastname
FROM contestant 
WHERE  name= @name  AND lastname = @lastname

    OPEN myCursor

    FETCH NEXT FROM myCursor INTO  /* what goes here?*/



    WHILE (@@FETCH_STATUS = 0) 
    BEGIN

 -- and here? 

        FETCH NEXT FROM myCursor INTO /* what goes here?*/


    END /*WHILE*/

    CLOSE myCursor
    DEALLOCATE myCursor


    INSERT INTO @tmpTable (name, lastname,prize, city)
    SELECT name, lastname,prize, city 
        FROM prize
        WHERE name = @name AND lastname = @lastname

    RETURN
END

回答1:

OK as long as you understand that:

The table designs are incorrect - you should have a contestant key in both tables.
A join is the solution to this, not a cursor
What I am providing here is the worst possible way to solve this and what you need to learn from this is that you should never use this as a solution to this problem!

But in answer to your question how do I use a cursor, here is some untested code that hopefully gives you the concept.

CREATE FUNCTION [dbo].[myFunction]
(
@name varchar (44),
@lastname varchar (44) 
)
RETURNS 
@tmpTable TABLE 
(   
name char(44),
lastname char(44),
prize varchar(44),
city char(44)
)
AS
BEGIN

DECLARE @c_name varchar (44)
DECLARE @c_lastname varchar (44) 


DECLARE myCursor CURSOR FOR

SELECT name, lastname
FROM contestant 
WHERE  name= @name  AND lastname = @lastname

OPEN myCursor

FETCH NEXT FROM myCursor INTO  @c_name, @c_lastname

WHILE (@@FETCH_STATUS = 0) 
BEGIN

    -- we've found a row. Name look for the matching row in prize
    INSERT INTO @tmpTable (name, lastname,prize, city)
    SELECT name, lastname,prize, city 
    FROM prize
    WHERE name = @c_name AND lastname = @c_lastname

    FETCH NEXT FROM myCursor INTO @c_name, @c_lastname

END /*WHILE*/

CLOSE myCursor
DEALLOCATE myCursor

RETURN
END

and as a comparison, here is the proper solution:

SELECT draw.name, draw.lastname, draw.prize, draw.city
FROM 
draw
INNER JOIN
contestant 
ON draw.name = contestant.name
AND draw.lastname = contestant.lastname
WHERE  contestant.name= 'John'  
AND contestant.lastname = 'Smith'

Its smaller, simpler and faster.

来源：https://stackoverflow.com/questions/13400842/my-first-table-valued-function-and-cursor

标签

sql-server

tsql

function

cursor

while-loop