Logging on to the Database
It is important to note that for most databases,
you will actually need to log on. That is, most databases implement
a security system that gives various users different privileges to do
different things such as READ ONLY or READ/WRITE.
Most likely, your database administrator will
have provided you with a login name and a password. She will
also have either provided you with the net address of the
database so you can log in remotely, or has given you a
direct command line shell.
Once you are logged in to a database, you
can begin to populate the database with data or extract already
existing data. Let's look first at populating the database.
Okay, let's define a simple relational
database that we can use to practice with...
We will define a database called "MY_COMPANY" with
four tables, "CLIENTS", "EMPLOYEES", "PRODUCTS", and "SALES". These tables will look something like the following:
| EMPLOYEES Table |
| EMP_NUM |
EMP_NAME |
EMP_COMMISSION |
EMP_SALARY |
| 001 |
Lim Li Chuen |
10% |
90,000 USD |
| 002 |
Lim Sing Yuen |
20% |
40,000 USD |
| 003 |
Loo Soon Keat |
20% |
50,000 USD |
| CLIENTS Table |
| C_NUM |
C_NAME |
C_ADDR |
C_CITY |
C_STATE |
C_ZIP |
C_PHONE |
| 001 |
Jason Lim |
100 W 10th St |
LA |
CA |
90027 |
456-7890 |
| 002 |
Rick Tan |
21 Jack St |
LA |
CA |
90031 |
649-2038 |
| 003 |
Stephen Petersen |
1029#A Kent Ave. |
LA |
CA |
90102 |
167-3333 |
| PRODUCTS Table |
| P_NUM |
P_QUANTITY |
P_PRICE |
| 001 |
104 |
99.99 |
| 002 |
12 |
865.99 |
| 003 |
2000 |
50.00 |
| SALES Table |
| S_NUM |
P_NUM |
S_QUANITY |
S_AMOUNT |
E_NUM |
C_NUM |
| 001 |
001 |
1 |
99.99 |
101 |
102 |
| 002 |
001 |
2 |
199.98 |
102 |
101 |
| 003 |
002 |
1 |
865.99 |
101 |
103 |
» 
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