Character and Binary String Types-Datatypes

The character datatypes in Oracle are CHAR, VARCHAR2, and their “N” variants. The CHAR and NCHAR can store up to 2000 bytes of text. The VARCHAR2 and NVARCHAR2 can store up to 4000 bytes of information.

Note Starting with Oracle 12c, VARCHAR2, NVARCHAR2, and RAW datatypes can be configured to store up to 32,767 bytes of information.

Extended datatypes are not enabled by default; therefore, unless explicitly configured, the maximum size is still 4000 bytes for VARCHAR2 and NVARCHAR2 datatypes and 2000 bytes for RAW. See the “Extended Datatypes” section later in this chapter for more details.

This text is converted between various character sets as needed by the database. A character set is a binary representation of individual characters in bits and bytes.

Many different character sets are available, and each is capable of representing different characters, for example:

•\ The US7ASCII character set is the ASCII standard representation of128 characters. It uses the low 7 bits of a byte to represent these 128characters.

•\ The WE8MSWIN1252 character set is a Western European characterset capable of representing the 128 ASCII characters as well as 128extended characters, using all 8 bits of a byte.

Before we get into the details of CHAR, VARCHAR2, and their “N” variants, it would benefit us to get a cursory understanding of what these different character sets mean to us.