7.3 Column types

MySQL supports a number of column types, which may be grouped into three categories: numeric types, date and time types, and string (character) types. This section first gives an overview of the types available and summarizes the storage requirements for each column type, then provides a more detailed description of the properties of the types in each category. The overview is intentionally brief. The more detailed descriptions should be consulted for additional information about particular column types, such as the allowable formats in which you can specify values.

The column types supported by MySQL are listed below. The following code letters are used in the descriptions:

M

Indicates the maximum display size. The maximum legal display size is 255.

D

Applies to floating-point types and indicates the number of digits following the decimal point. The maximum possible value is 30, but should be no greater than M-2.

Square brackets (`[' and `]') indicate parts of type specifiers that are optional.

Note that if you specify ZEROFILL for a column, MySQL will automatically add the UNSIGNED attribute to the column.

TINYINT[(M)] [UNSIGNED] [ZEROFILL]

A very small integer. The signed range is -128 to 127. The unsigned range is 0 to 255.

SMALLINT[(M)] [UNSIGNED] [ZEROFILL]

A small integer. The signed range is -32768 to 32767. The unsigned range is 0 to 65535.

MEDIUMINT[(M)] [UNSIGNED] [ZEROFILL]

A medium-size integer. The signed range is -8388608 to 8388607. The unsigned range is 0 to 16777215.

INT[(M)] [UNSIGNED] [ZEROFILL]

A normal-size integer. The signed range is -2147483648 to 2147483647. The unsigned range is 0 to 4294967295.

INTEGER[(M)] [UNSIGNED] [ZEROFILL]

This is a synonym for INT.

BIGINT[(M)] [UNSIGNED] [ZEROFILL]

A large integer. The signed range is -9223372036854775808 to 9223372036854775807. The unsigned range is 0 to 18446744073709551615. Note that all arithmetic is done using signed BIGINT or DOUBLE values, so you shouldn't use unsigned big integers larger than 9223372036854775807 (63 bits) except with bit functions! Note that -, + and * will use BIGINT arithmetic when both arguments are INTEGER values! This means that if you multiply two big integers (or results from functions that return integers) you may get unexpected results if the result is larger than 9223372036854775807.

FLOAT(precision) [ZEROFILL]

A floating-point number. Cannot be unsigned. precision can be <=24 for a single precision floating point number and between 25 and 53 for a double precision floating point number. these types are like the FLOAT and DOUBLE types described immediately below. FLOAT(X) have the same ranges as the corresponding FLOAT and DOUBLE types, but the display size and number of decimals is undefined. In MySQL 3.23, this is a true floating point value. In earlier MySQL versions, FLOAT(precision) always has 2 decimals. This syntax is provided for ODBC compatibility.

FLOAT[(M,D)] [ZEROFILL]

A small (single-precision) floating-point number. Cannot be unsigned. Allowable values are -3.402823466E+38 to -1.175494351E-38, 0 and 1.175494351E-38 to 3.402823466E+38. The M is the display width and D is the number of decimals. FLOAT without an argument or with an argument of <= 24 stands for a single-precision floating point number.

DOUBLE[(M,D)] [ZEROFILL]

A normal-size (double-precision) floating-point number. Cannot be unsigned. Allowable values are -1.7976931348623157E+308 to -2.2250738585072014E-308, 0 and 2.2250738585072014E-308 to 1.7976931348623157E+308. The M is the display width and D is the number of decimals. DOUBLE without an argument or FLOAT(X) where 25 <= X <= 53 stands for a double-precision floating point number.

DOUBLE PRECISION[(M,D)] [ZEROFILL]

REAL[(M,D)] [ZEROFILL]

These are synonyms for DOUBLE.

DECIMAL[(M[,D])] [ZEROFILL]

An unpacked floating-point number. Cannot be unsigned. Behaves like a CHAR column: ``unpacked'' means the number is stored as a string, using one character for each digit of the value. The decimal point, and, for negative numbers, the `-' sign is not counted in M. If D is 0, values will have no decimal point or fractional part. The maximum range of DECIMAL values is the same as for DOUBLE, but the actual range for a given DECIMAL column may be constrained by the choice of M and D. If D is left out it's set to 0. If M is left out it's set to 10. Note that in MySQL 3.22 the M argument includes the sign and the decimal point.

NUMERIC(M,D) [ZEROFILL]

This is a synonym for DECIMAL.

DATE

A date. The supported range is '1000-01-01' to '9999-12-31'. MySQL displays DATE values in 'YYYY-MM-DD' format, but allows you to assign values to DATE columns using either strings or numbers.

DATETIME

A date and time combination. The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'. MySQL displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' format, but allows you to assign values to DATETIME columns using either strings or numbers.

TIMESTAMP[(M)]

A timestamp. The range is '1970-01-01 00:00:00' to sometime in the year 2037. MySQL displays TIMESTAMP values in YYYYMMDDHHMMSS, YYMMDDHHMMSS, YYYYMMDD or YYMMDD format, depending on whether M is 14 (or missing), 12, 8 or 6, but allows you to assign values to TIMESTAMP columns using either strings or numbers. A TIMESTAMP column is useful for recording the date and time of an INSERT or UPDATE operation because it is automatically set to the date and time of the most recent operation if you don't give it a value yourself. You can also set it to the current date and time by assigning it a NULL value. See section 7.3.6 Date and time types.

TIME

A time. The range is '-838:59:59' to '838:59:59'. MySQL displays TIME values in 'HH:MM:SS' format, but allows you to assign values to TIME columns using either strings or numbers.

YEAR[(2|4)]

A year in 2- or 4- digit formats (default is 4-digit). The allowable values are 1901 to 2155, and 0000 in the 4 year format and 1970-2069 if you use the 2 digit format (70-69). MySQL displays YEAR values in YYYY format, but allows you to assign values to YEAR columns using either strings or numbers. (The YEAR type is new in MySQL 3.22.)

[NATIONAL] CHAR(M) [BINARY]

A fixed-length string that is always right-padded with spaces to the specified length when stored. The range of M is 1 to 255 characters. Trailing spaces are removed when the value is retrieved. CHAR values are sorted and compared in case-insensitive fashion according to the default character set unless the BINARY keyword is given. NATIONAL CHAR (short form NCHAR) is the ANSI SQL way to define that a CHAR column should use the default CHARACTER set. This is default in MySQL. CHAR is a shorthand for CHARACTER. MySQL allows you to create a column of type CHAR(0). This is mainly useful when you have to be compliant with some old applications that depend on the existence of a column but that do not actually use the value. This is also quite nice when you need a column that only can take 2 values: A CHAR(0), that is not defined as NOT NULL, will only occupy one bit and can only take 2 values: NULL or "".

[NATIONAL] VARCHAR(M) [BINARY]

A variable-length string. Note: Trailing spaces are removed when the value is stored (this differs from the ANSI SQL specification). The range of M is 1 to 255 characters. VARCHAR values are sorted and compared in case-insensitive fashion unless the BINARY keyword is given. See section 7.7.1 Silent column specification changes. VARCHAR is a shorthand for CHARACTER VARYING.

TINYBLOB

TINYTEXT

A BLOB or TEXT column with a maximum length of 255 (2^8 - 1) characters. See section 7.7.1 Silent column specification changes.

BLOB

TEXT

A BLOB or TEXT column with a maximum length of 65535 (2^16 - 1) characters. See section 7.7.1 Silent column specification changes.

MEDIUMBLOB

MEDIUMTEXT

A BLOB or TEXT column with a maximum length of 16777215 (2^24 - 1) characters. See section 7.7.1 Silent column specification changes.

LONGBLOB

LONGTEXT

A BLOB or TEXT column with a maximum length of 4294967295 (2^32 - 1) characters. See section 7.7.1 Silent column specification changes.

ENUM('value1','value2',...)

An enumeration. A string object that can have only one value, chosen from the list of values 'value1', 'value2', ..., or NULL. An ENUM can have a maximum of 65535 distinct values.

SET('value1','value2',...)

A set. A string object that can have zero or more values, each of which must be chosen from the list of values 'value1', 'value2', ... A SET can have a maximum of 64 members.

• 7.3.1 Column type storage requirements
• 7.3.2 Numeric types
• 7.3.3 Date and time types
• 7.3.4 String types
• 7.3.5 Numeric types
• 7.3.6 Date and time types
• 7.3.7 String types
• 7.3.8 Choosing the right type for a column
• 7.3.9 Column indexes
• 7.3.10 Multiple-column indexes
• 7.3.11 Using column types from other database engines

Comments