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VARCHAR2 data type

Last Updated: Jun 18, 2021

The VARCHAR2 data type stores variable-length strings. The maximum string length is 32,767 bytes. When you create a VARCHAR2 column, you must specify the maximum length for the VARCHAR2 column. Although you can store a zero-length string (''), the maximum value must be at least 1 byte. ApsaraDB for OceanBase stores each value in the column in the way as you specify.

Notice

  • From a technical point of view, a character is a code point of the database character set.

  • Assume that you create a database object with a VARCHAR2 column or attribute. If you specify no explicit qualifiers in the column or attribute definition, the value of the NLS_LENGTH_SEMANTICS parameter of the session determines the length semantics.

  • ApsaraDB for OceanBase compares the VARCHAR2 values by using non-padded comparison semantics.

  • When you convert data between databases that use different character sets, you must ensure that the VARCHAR2 data consists of well-formed strings.

Syntax

VARCHAR2(size [BYTE | CHAR])

Parameters

Parameter

Description

size

The number of the stored bytes or characters.

BYTE

Specifies that the column length is measured in bytes.

CHAR

Specifies that the column length is measured in characters.

Examples

You can specify the maximum length in characters by using the CHAR qualifier.

VARCHAR2(10 CHAR)

You can specify the maximum length in bytes by using the BYTE qualifier.

VARCHAR2(10 BYTE)