Data Types

First, we need to cover the various data types available (see Table 3-1). Data types are like variable types. In some languages, you have strings, integers, floating-point numbers, big integers, characters, and so on. The same holds true for database data types: There are different data descriptors for different types of data. Every column in the database is for storing a particular kind of data: a column for storing last names would be of type 'varchar', a column for storing birthdates should be of type 'date', and so on. This helps the database store the information more efficiently and helps the programmer know what kind of data to expect.

Table 3-1: Common Data Types

Name

Type

Description

Notes

INT

Numeric

Signed four-byte integer

-2147483648 to +2147483647

SMALLINT

Numeric

Signed two-byte integer

-32768 to +32767

REAL

Numeric

Variable precision

6 decimal digits precision

CHAR(n)

Character

Fixed-length char string

Holds n characters

VARCHAR(n)

Character

Variable-length char string

Holds up to n characters

BLOB

Binary

Binary Large OBject

For storing large binary data

Name

Type

Description

Notes

DATE

Date

Date storage

Ex. YYYY-MM-DD

TIME

Time

Time storage

Ex. HH:MM:SS

TIMESTAMP

Date/Time

Date & Time storage

Ex. YYYY-MM-DD HH:MM:SS



Perl Database Programming
Perl Database Programming
ISBN: 0764549561
EAN: 2147483647
Year: 2001
Pages: 175

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