All tables within a database must
be created at some point in time...let's
see how we would create the Orders
table:
CREATE TABLE ORDERS
(OWNERID INTEGER NOT NULL,
ITEMDESIRED CHAR(40) NOT NULL);
This statement gives
the table name and tells the DBMS
about each column in the table. Please
note that this statement uses
generic data types, and that the data
types might be different, depending
on what DBMS you are using. As usual,
check local listings. Some common
generic data types are:
-
Char(x) - A
column of characters, where x
is a number designating the maximum
number of characters allowed (maximum
length) in the column.
-
Integer - A
column of whole numbers, positive
or negative.
-
Decimal(x,
y) - A column of decimal numbers,
where x is the maximum length
in digits of the decimal numbers
in this column, and y is the maximum
number of digits allowed after
the decimal point. The maximum
(4,2) number would be 99.99.
-
Date - A date
column in a DBMS-specific format.
-
Logical - A
column that can hold only two
values: TRUE or FALSE.
One other note, the
NOT NULL means that the column must
have a value in each row. If NULL
was used, that column may be left
empty in a given row. |