Learning by sample t-sql - part 2

w w w . B u k a n S e m b a r a n g . I n f o © 2 0 1 0

Learning By Sample -

T-SQL : Part 2

Learning By Sample Series


Page 1

Learning By Sample - T-SQL : Part 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 10-15 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.


Page 2


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 2000. 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 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 !


Page 3


Grouping

1. Make sure that you already open SQL Server Management Studio

2. Let’s to have an aggregation, but we still want to display another field in each aggregation, thus we

need grouping inside the query. This process named as grouping which will be placed in the end of

our query and of course, it’s easy. You don’t believe it ? Come on try it….

a. Displaying each customer’s sales omzet

Here is the partial result :

b. But, what if I just want to display two digits after the decimal sign ? Then we need CAST

function to limit the digit :


Page 4


Pay attention to of CAST usage which converting the output field into other format. In this

case, we convert it into decimal format and limit the digit after decimal sign by only two

digits.

Let see how it works :

c. Displaying sales omzet for each customer in any products except for products which

included in Seafood category


Page 5


• First, take a look of which fields will be displayed, Distinct keyword used as

customer will be only display once in query result :

• Then see, how the aggregate come :


Page 6


• Next, see the multiple table technique (based on the same field in each

tables):

• Afterward, we give the condition :


Page 7


• Finally, give the grouping and sort it based on customer’s name :

See the result here :

d. Shall we try another sample ? Okay then, try to display sales omzet from all customers

which come from Argentina.


Page 8


Here is the result :

e. Want another sample ? Ok, I give you the last one. Can you display sales omzet for each

category just in year of 1998, and let’s display it only by two digits decimal using Cast

keyword.


Page 9


Take a look the result :

3. Well, I think you need a break and it’s time for me to drink a cup of hot black coffe and smoking a

little bit, see you in next tutorial…..

Learning by sample t-sql - part 2

Education

Transcript of Learning by sample t-sql - part 2