Learning By Sample Series. Learning By Sample - T-SQL : Part 3

Transcription

1 Learning By Sample Series Learning By Sample - T-SQL : Part 3 w w w. B u k a n S e m b a r a n g. I n f o

2 Foreword Learning By Sample? So, why should I made this tutorial freely accessed by everyone? Well, surely I am just nobody, I also just another ordinary person with ordinary knowledge. However, I always feel that some persons in the internet giving away their tutorial for free and I feel being helped by them. Then, I remember one of my senior wisdom words : If you want to be given more, then start to give more. And of course, I really believe those words, since that I already proof it to be right all the time. Also, I m not an English native speaker, however, I just try to improve my English in any other way, especially in written format. Thus, I think writing is the best practice to improve my English freely. However, you will find many grammatical errors in my tutorial, so please send me comments and also suggestion to improve it. Then, why the format using Learning By Sample series? Is it really different with other tutorials out there? Ehm, I already wrote three books (in Indonesian) using this kind of format, and many readers already contact me about how this format really help them to learn from the scratch. So, why in the world I m not re-create it in English format, right? Eventhough actually, it is similar with Hands On Lab series which already famous in Microsoft site previously. All of my lesson also being designed as short samples and short time exercise. Thus, I hope that each of tutorial series would take only at least minutes maximum to learn. Why keep it short? Because many beginner (and even expert) will find boring whenever they must keep studying more than 15 minutes (but you will never get bored when you online in such time right?). Another reason is just because many of samples in this series come up from my lecturing task exercise. So, I just try to compile all my lab exercises in order to keep it tidy and also reusable for my students. That s why you will find many unsorted course material inside these series, however, just take a seat and enjoy the ride! Requirements So, what will you need before starting this simple tutorial? First, you need a PC/laptop/netbook which use at least Windows XP/Vista/Seven/Server as its operating system. And, you should also install SQL Server (at least Express Edition) from version 2005 and above. And remember, if you have SQL Server Express Edition, make sure that you already download and install its SQL Server Management Studio too. w w w. B u k a n S e m b a r a n g. I n f o Page 1

3 Is that enough? Of course not, you also need Northwind database attached to your database server (which you can download it from download section of this website) that already widely being used as sample database from SQL Server And if you ask, why use Northwind database instead of Adventure Work database, the main reason is just because its simplicity. Northwind database contains small number of tables and also it only covers small amount of records, thus beginner will feel comfortable and fast in doing this lesson. So, if you already download your Northwind script, then just open your SQL Server Management Studio and then open the northwind.sql script file. Afterward, execute the script by pressing F5 key, and that s it, you will have a newly Northwind database attached to your SQL server. Prior Knowledge needed If you really want to follow this series, then you should aware that basic SQL knowledge really needed. For example, this HOL wil not include any basic knowledge about T-SQL basic command and also about the basic of SQL server. And also, you should know the relationship diagram of Northwind database before you understand this lesson. You can learn about Northwind relationship by creating Database Diagram in SQL Server Management Studio. Please refer to previous lesson on how to create the diagram. You also ought to know basic Select command (includes multiple table and aggregation) from previous lesson (if you are really a beginner), however, if you feel good enough in SQL and merely trying to improve your skill then just follow the exercises later. Have fun! w w w. B u k a n S e m b a r a n g. I n f o Page 2

4 Learning By Sample - T-SQL : Part 3 Sub Query 1. Sub query concept is easy, just assume that you have another query which being placed in other query. But, why should we have sub query? Take a deep breath and come on try these samples : a. Display product which never been sold in 1998 Check the product which have been sold in 1998 at first Then, combine it with the master table which is product Take a closer look to not in keyword which become the main actor in this query Page 3

5 Here is the result : b. Want another sample? Let s show customer s name which never have sales in 1997 Just like previous sample, display the opposite condition : customer s name which have sales transaction in 1997 Then use not in keyword to display the reverse condition from its master table Check the result : w w w. B u k a n S e m b a r a n g. I n f o Page 4

6 c. Okay, next try this sample which use two condition. Present product s category which already have been bought by customer from Spain in 1997 Here is the result : d. Displaying sales percentage for each customer in 1998, this kind of display commonly needed in charting process. w w w. B u k a n S e m b a r a n g. I n f o Page 5

7 First, check the whole omzet sales summary in This will be the sub query which will be placed as arithmetic operation, not as condition. Then summarize each product s category sales omzet w w w. B u k a n S e m b a r a n g. I n f o Page 6

8 Next, let s combine both query. Want to take a look of its result? w w w. B u k a n S e m b a r a n g. I n f o Page 7

9 Just pay attention to the division operation between sum for each category and whole sales omzet which come from sub query. It s easy right? e. Okay, let s try another exercise. Try to display employee name which never sold anything to Portugal w w w. B u k a n S e m b a r a n g. I n f o Page 8

10 Here is the result : So, where s the sub query go? Let me show you f. Well, sound easy right? Then try this last one. Displaying sales omzet for all product which have been sold to Norway in percentage format. w w w. B u k a n S e m b a r a n g. I n f o Page 9

11 Check the result : w w w. B u k a n S e m b a r a n g. I n f o Page 10

12 2. Well, I think that s enough for a moment and it s time for me to take a short nap in this beautiful Sunday, see you in next tutorial.. w w w. B u k a n S e m b a r a n g. I n f o Page 11