SQL题目解析：计算、分组与交叉表报告

[转] SQL Server试题 
Question 1：
Can you use a batch SQL or store procedure to calculating the Number of Days in a Month
Answer   1：
找出当月的天数


select datepart(dd,dateadd(dd,-1,dateadd(mm,1,cast(cast(year(getdate()) as varchar)+'-'+cast(month(getdate()) as varchar)+'-01' as datetime))))

Question2：
Can you use a SQL statement to calculating it ？
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  2：

select bookid,bookname,price=case when price is null then 'unknown' 
       when  price between 10 and 20 then '10 to 20' else price end
from books

Question3：
Can you use a SQL statement to finding duplicate values!
How can I find authors with the same last name?
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  3：

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 quarter and 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 4：
用动态SQL实现

Question5: 
The Fastest Way to Recompile All Stored Procedures
I have a problem with a database running in SQL Server 6.5 (Service Pack 4). 
We moved the database (object transfer) from one machine to another last night, and an error (specific to a stored procedure) is cropping up. 
However, I can't tell which procedure is causing it. 
Permissions are granted in all of our stored procedures; is there a way from the isql utility to force all stored procedures to recompile?
Tips: sp_recompile can recomplie a store procedure each time
Answer 5：
在执行存储过程时,使用 with recompile 选项强制编译新的计划；使用sp_recompile系统存储过程强制在下次运行时进行重新编译

Question6: