ALTER procedure CalcDays
(
 @Year int,
 @Month int
)
as
begin
 if @Month>12 or @Month<1
 begin
  print 'Month值應該在1～12之間！';
  return
 end
 
 declare @NextMonth int;
 declare @NextYear int;
 if @Month=12
 begin
  set @NextMonth=1;
  set @NextYear=@Year+1;
 end
 else
 begin
  set @NextMonth=@Month+1;
  set @NextYear=@Year
 end

 declare @StartDate nchar(9);
 declare @EndDate nchar(9);
 set @StartDate=Cast(@Month as nchar(2)) + '/1/' + Cast(@Year as nchar(4));
 set @EndDate=Cast(@NextMonth as nchar(2)) + '/1/' + Cast(@NextYear as nchar(4));
 SELECT DATEDIFF(day, Cast(@StartDate as datetime), Cast(@EndDate as datetime)) AS NumberOfDays
end

Question 2:
  Can you use a SQL statement to calculating it! (SQL Server 2K中的pubs數據庫，下同)
  How can I print "10 to 20" for books that sell for between $10 and $20，"unknown" for books whose price is null, and "other" for all other prices?

Answer：

select title, price as '此列僅供參考用',price=
 case 
  when price is null then 'unknown'
  when price>10 and price<20 then '10 to 20'
  else 'other'
 end
from titles

Question 3：     
  How can I find authors with the same last name?(SQL Server 2K中的pubs數據庫，下同)
  You can use the table authors in datatabase pubs. I want to get the result as below:
  Output:
  au_lname                                 number_dups
  ---------------------------------------- -----------
  Ringer                                   2
  (1 row(s) affected)

Answer：

  select au_lname,number_dups=count(1) from authors group by au_lname

   
   
Question4：
  Can you create a cross-tab report in my SQL Server!
  How can I get the report about sale quality for each store and each quarterand the total sale quality for each quarter at year 1993?
  You can use the table sales and stores in datatabase pubs.
  Table Sales record all sale detail item for each store. Column store_id is the id of each store, ord_date is the order date  of each sale item, and column qty is the sale qulity. Table stores record all store information.
  I want to get the result look like as below:
Output:
stor_name                                        Total       Qtr1        Qtr2        Qtr3        Qtr4       
------------------------------------------ ----------- ----------- ----------- ----------- -----------
Barnum's                                             50          0           50          0             0
Bookbeat                                             55          25          30         0             0
Doc-U-Mat: Quality Laundry and Books  85           0           85          0             0
Fricative Bookshop                               60          35          0           0            25
Total                                                 250         60          165         0           25

Answer：(可以動態拼接SQL來實現，也可以使用SQL Server 2K5中的PIVOT)

select stor_name, isnull([1],0)+isnull([2],0)+isnull([3],0)+isnull([4],0) as 'Total', 
 isnull([1],0) as 'Qtr1', isnull([2],0) as 'Qtr2', isnull([3],0) as 'Qtr3', isnull([4],0) as 'Qtr4'
from
(select stor_name,sales.stor_id,DATEPART(qq, ord_date) as Quarty,qty from sales,stores
  where sales.stor_id=stores.stor_id and year(sales.ord_date)=1993) as tmp
pivot
(
 sum(qty) for Quarty in ([0],[1],[2],[3],[4])
) as pvt
union
select 'total', sum(isnull([1],0))+sum(isnull([2],0))+sum(isnull([3],0))+sum(isnull([4],0)) as 'Total', 
 sum(isnull([1],0)) as 'Qtr1', sum(isnull([2],0)) as 'Qtr2', sum(isnull([3],0)) as 'Qtr3', sum(isnull([4],0)) as 'Qtr4'
from
(select sales.stor_id,DATEPART(qq, ord_date) as Quarty,qty from sales,stores
  where sales.stor_id=stores.stor_id and year(sales.ord_date)=1993) as tmp
pivot
(
 sum(qty) for Quarty in ([0],[1],[2],[3],[4])
) as pvt

   
   
Question 5:
How can I add row numbers to my result set?
In database pubs, have a table titles , now I want the result shown as below,each row have a row number, how can you do that?
Result:
line-no     title_id
----------- --------
1           BU1032
2           BU1111
3           BU2075
4           BU7832
5           MC2222
6           MC3021
7           MC3026
8           PC1035
9           PC8888
10          PC9999
11          PS1372
12          PS2091
13          PS2106
14          PS3333
15          PS7777
16          TC3218
17          TC4203
18          TC7777

Answer：

--可以直接用SQL Server 2005提供的row_number()函數
select row_number() as line_no ,title_id from titles
--SQL Server 2000中可以借助于臨時表
select line_no identity(int,1,1),title_id into #t from titles
select * from #t
drop table #t

   
Question 6:
Can you tell me what the difference of two SQL statements at performance of execution?
Statement 1:
if NOT EXISTS ( select * from publishers where state = 'NY')
    begin
        SELECT 'Sales force needs to penetrate New York market'
    end
else
    begin
        SELECT 'We have publishers in New York'
    end
Statement 2:
if EXISTS ( select * from publishers where state = 'NY')
    begin
        SELECT 'We have publishers in New York'
    end
else
    begin
        SELECT 'Sales force needs to penetrate New York market'
    end

Answer：(我也不知道答案。)
    一個說法是NOT EXISTS內部是由EXISTS來實現的，但我在publishers表中構造了4+百萬條記錄，上面兩條SQL的執行計劃完全相同(In Server Server 2005)，各執行計劃的占50%，并沒有發現有差異。

Question 7: 
  How can I list all California authors regardless of whether they have written a book?
  Indatabase pubs, have a table authors and titleauthor , table authors has a column state, and titleauthor have books each author written.
  CA behalf of california in table authors.

Answer ：
  “標準”答案是：SELECT * FROM  authors WHERE state='CA' AND EXISTS
 (SELECT * FROM titleauthor WHERE authors.au_id=titleauthor.au_id)
  但我覺得題目有問題，按照題目的意思，只要找出State='CA'的Authors就行了(regardless of whether they have written a book)，select * from  authors where state='CA'，沒有必要去Join其他的表。

   
Question 8：
  How can I get a list of the stores that have bought both 'bussiness' and 'mod_cook' type books?
  In database pubs, use three table stores,sales and titles to implement this requestment.
  Now I want to get the result as below:    
  stor_id   stor_name                                                                  
  -------   ----------------------------------------    
  ...  
  7896         Fricative   Bookshop  
  ...  
  ...  
  ...  

Answer：(也可以不用臨時表，而改用SQL Server 2005中的CTE)

select sales.stor_id,titles.[type] into #SaleTitle from sales,titles
 where sales.title_id = titles.title_id;
select distinct stores.stor_id, stores.stor_name from stores,#SaleTitle 
 where
 'business' in (select #SaleTitle.[type] from #SaleTitle  where stores.stor_id=#SaleTitle.stor_id)
 and
 'mod_cook' in (select #SaleTitle.[type] from #SaleTitle  where stores.stor_id=#SaleTitle.stor_id);
drop table #SaleTitle;

   
Question 9:
 How can I list non-contignous data?
In database pubs, I create a table test using statement as below, and I insert several row as below
create table test
( id int primary key )
go

insert into test values (1 )
insert into test values (2 )
insert into test values (3 )
insert into test values (4 )
insert into test values (5 )
insert into test values (6 )
insert into test values (8 )
insert into test values (9 )
insert into test values (11)
insert into test values (12)
insert into test values (13)
insert into test values (14)
insert into test values (18)
insert into test values (19)
go

Now I want to list the result of the non-contignous row as below,how can I do it?
Missing after Missing before
------------- --------------
6             8
9             11
...

Answer：

select Test1.id as 'Missing after', Test2.id as 'Missing before' 
from test as Test1,test as Test2 where Test1.id+1 not in (select ID from Test) 
 and Test2.id=(select min(id) from test where id>Test1.id)

    
   
Question10:
How can I list all book with prices greather than the average price of books of the same type?
Indatabase pubs, have a table named titles , its column named price meanthe price of the book, and another named type mean the type of books.
Now I want to get the result as below:
type         title                                                                            price                
------------ -------------------------------------------------------------------------------- ---------------------
business     The Busy Executive's Database Guide                                              19.9900
...
...
...
...

Answer：

WITH AvgPrice(type,price) 
AS
(
    SELECT [type], AVG(price) AS 'price' FROM titles GROUP BY [type]
)
SELECT titles.type,title,titles.price FROM titles
    JOIN AvgPrice ON titles.price>AvgPrice.price AND titles.[type]=AvgPrice.[type];
或：
select a.type,a.title,a.price from titles a,
(select type,price=avg(price) from titles group by type)b
where a.type=b.type and a.price>b.price;