Question

我有这个问题：

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

我从上面的查询中得到了几个结果，我需要将它们用于以下查询：

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

现在我正在用光标和WHILE构建一个表值函数，所以我可以得到一个包含结果的表。

这是我的尝试，你能帮我完成吗？为了理解这个TSQL章节，对我来说非常有帮助。谢谢！

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

Answer 1

好的，只要你明白：

表格设计不正确 - 您应该在两个表格中都有参赛者密钥。
联接是解决方案，而不是游标
我在这里提供的是解决这个问题的最糟糕的方法，你需要从中学到的是你永远不应该用它来解决这个问题！

但是在回答你的问题我如何使用游标时，这里有一些未经测试的代码，希望能为你提供这个概念。

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

作为比较，这是正确的解决方案：

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'

它更小，更简单，更快。

我的第一个表值得函数和光标

1 个答案: