16.2 String Data Types

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String data types store various kinds of text data. There are several types to accomodate data of different sizes. For each size , there is a type that sorts and compares entries in a case-insensitive fashion in accordance with the sorting rules for the default character set and a corresponding binary type that does simple byte-by-byte sorts and comparisons. In other words, binary values are case sensitive. For CHAR and VARCHAR , the binary types are declared using the BINARY attribute. The TEXT types, however, have corresponding BLOB types as their binary counterparts.

BLOB

Binary form of TEXT .

CHAR

Syntax

 CHAR(  size  ) [BINARY]

Size

Specified by the size value in a range of to 255 (1 to 255 prior to MySQL 3.23)

Storage

size bytes

Description

A fixed-length text field. String values with fewer characters than the column's size will be right padded with spaces. The right padding is removed on retrieval of the value from the database.

CHAR(0) fields are useful for backward compatibility with legacy systems that no longer store values in the column.

CHARACTER

Synonym for CHAR .

CHARACTER VARYING

Synonym for VARCHAR .

LONGBLOB

Binary form of LONGTEXT .

LONGTEXT

Syntax

 LONGTEXT

Size

0 to 4,294,967,295

Storage

Length of value + 4 bytes

Description

Storage for large text values. While the theoretical limit on the size of the text that can be stored in a LONGTEXT column exceeds 4 GB, the practical limit is much less due to limitations of the MySQL communication protocol and the amount of memory available on both the client and server ends of the communication.

MEDIUMBLOB

Binary form of MEDIUMTEXT .

MEDIUMTEXT

Syntax

 MEDIUMTEXT

Size

0 to 16,777,215

Storage

Length of value + 3 bytes

Description

Storage for medium- sized text values.

NCHAR

Synonym of CHAR .

NATIONAL CHAR

Synonym of CHAR .

NATIONAL CHARACTER

Synonym of CHAR .

NATIONAL VARCHAR

Synonym of VARCHAR .

TEXT

Syntax

 TEXT

Size

0 to 65,535

Storage

Length of value + 2 bytes

Description

Storage for most text values.

TINYBLOB

Binary form of TINYTEXT .

TINYTEXT

Syntax

 TINYTEXT

Size

0 to 255

Storage

Length of value + 1 byte

Description

Storage for short text values.

VARCHAR

Syntax

 VARCHAR(  size  ) [BINARY]

Size

Specified by the size value in a range of to 255 (1 to 255 prior to MySQL 3.23)

Storage

Length of value + 1 byte

Description

Storage for variable-length text. Trailing spaces are removed from VARCHAR values when stored in a database that conflicts with the ANSI specification.

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