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CHAR data type

Last Updated: Jun 18, 2021

The CHAR data type stores fixed-length strings. ApsaraDB for OceanBase ensures that all values stored in a CHAR column have the fixed length specified by size. If you insert a value that is shorter than the specified length, ApsaraDB for OceanBase pads the value to the specified length with spaces. If you insert a value that exceeds the specified length, ApsaraDB for OceanBase returns an error.

The BYTE and CHAR qualifiers override the semantics specified by the NLS_LENGTH_SEMANTICS parameter, which defaults to the BYTE semantics. To ensure proper data conversion between databases that use different character sets, the CHAR data must consist of well-formed strings.

Syntax

CHAR [(size [BYTE | CHAR])]

Parameters

Parameter

Description

size

A fixed length.

BYTE

Specifies that the column length is measured in bytes.

CHAR

Specifies that the column length is measured in characters.

The default length of a CHAR column is 1 byte. The maximum length is 2,000 bytes.

Examples

By default, when you create a table that contains a CHAR column, you specify the column length in bytes. BYTE is the default qualifier.

If you use the CHAR qualifier, you specify the column length in characters.

  • Example 1

Assume that you insert a 1-byte string into the CHAR(10) column. Before the string is stored, the system pads the string to 10 bytes with spaces.

  • Example 2

CHAR(10 CHAR) indicates that you specify the column length in characters.