Getting Started with DB2 Express-C

Chapter 8 – Working with Database Objects 159
quantity
cost
image
project_num
INTEGER, NOT NULL
DECIMAL, Precision 7, Scale 2, NOT NULL
BLOB, 1MB, NULLABLE, NOT LOGGED
CHAR, length 6, NOT NULL
Note: The NOT LOGGED option can be specified when declaring LOB columns. It
is mandatory for columns greater than 1GB in size. It is also generally
recommended for LOBs larger than 10MB, as changes to large columns can quickly
fill the log file. Even if NOT LOGGED is used, changes to LOB files during a
transaction can still be successfully rolled back. Also notice that the image column
is the only one defined as a NULLABLE column. Why do you think that the column
was defined like this?
7. At this point, all the mandatory information for creating a table has been provided.
By skipping the other panels in the wizard, you are choosing the default values for
those options. You can always add keys and constraints after a table has been
created.
8. Add a constraint to the table to restrict values on the quantity column. On the
Constraint page of the wizard, click the ADD button. In the Check Name field,
enter: valid_quantities. In the Check Condition field, enter: quantity > 0
Click the OK button. You should see a summary of the constraint you just added in
the Constraint page of the wizard. Click the Next button to continue to the next
page of the wizard.
9. You can continue going through the wizard, changing the other parameters of the
table. Alternatively, you can skip to the Summary page, or simply click the Finish
button to create the table.
10. From Control Center, click on the Tables folder under the SAMPLE database in the
Object Tree pane. The table you just created should now appear in the list. It might
be necessary to refresh the Control Center view in order to see the changes.
11. Let's now test implicit casting using the table STAFF in the SAMPLE database. Try
the following:
C:\>db2 describe table staff
Note that the ID column is defined as a SMALLINT
C:\>db2 select * from staff where id = '350' --> Note '350' is a string
C:\>db2 select * from staff where id = 350 --> Note 350 is a number
In both cases, the output should be:
ID NAME DEPT JOB YEARS SALARY COMM