SPECIAL IMPLEMENTATION CONSIDERATIONS - Database Design and Development: An Essential Guide for IT Professionals - page 389

Data Types SQL supports a variety of data types for the table columns repre-
senting the attributes. In the database, legal values may be entered for each column
based on the declared data type. The standard versions of SQL allow for accepted
data types; in addition, specific vendor implementation may have additional data
types or some variations of a standard data type.
The following is a list of the common SQL data types:

Character data

CHAR( n ) Alphanumeric character data of fixed length n

VARCHAR ( n ) Alphanumeric character data of variable length up to a

maximum length of n

Numeric data

DECIMAL ( m , n ) Signed number, where m is the total number of digits

including the sign and n is the number of digits to the right
of the decimal point

INTEGER Large positive or negative whole numbers up to 11 digits

SMALLINT Small positive or negative whole numbers up to 5 or 6 digits

FLOAT ( m ) Floating point number represented in scientific notation

with specified precision of at least m digits

Date/time data

DATE Calendar date showing year, month, and day in a prescribed

format (year/month/day, month/day/year, or day/month/
year)

TIME Hour, minute, second with time zone

Interval data

INTERVAL Representation of periods of time

Bit data

BIT ( n ) Bit string of fixed length n

Logical data

LOGICAL “True” or “False” values

SQL Data Definition Example You have now gone through the various SQL
statements available for defining database objects. You have also noted the provi-
sions to indicate the different data types for values to be stored in the database. Let
us put what we have covered so far in a practical example. In Figure 11-5, you
studied an entity-relationship diagram for a florist business. Also, Figure 11-10 pre-
sents the relational schema for that business. We will refer to those figures and create
data definitions with SQL statements. While doing so, we will provide examples of
most of the data definition statements listed above.
Carefully observe all the statements now shown in Figure 13-9. This figure pre-
sents the definition of the schema with the tables, columns, indexes, and so on for