( show you various data types in MySQL so that you can apply them effectively in designing database tables.)
Summary: in this tutorial, you will learn about MySQL data types and how to use them effectively in designing databases in MySQL.
Introduction
The data type of a column defines what value the column can hold: integer, character, money, date and time, binary, and so on. Each column in a database table is required to have a name and a data type.
An SQL developer must decide what type of data that will be stored inside each column when creating a table. The data type is a guideline for SQL to understand what type of data is expected inside of each column, and it also identifies how SQL will interact with the stored data. In MySQL the followings are the available data types
1. String Data types
- Numeric Data Types
- Date and Time Data Types
- Boolean Data Type
- Spatial Data Types
- JSON Data Type
In MySQL, there are several data types that can be used to define the type of data a column can hold. Here are some common data types:
- Numeric Types:
- INT: Integer type, for whole numbers.
- BIGINT: Large integer type.
- DECIMAL: Fixed-point exact numeric, suitable for monetary values.
- FLOAT: Floating-point numeric, suitable for approximate values.
- DOUBLE: Double-precision floating-point numeric.
- String Types:
- VARCHAR: Variable-length string.
- CHAR: Fixed-length string.
- TEXT: Variable-length text.
- Date and Time Types:
- DATE: Date value in 'YYYY-MM-DD' format.
- TIME: Time value in 'HH:MM:SS' format.
- DATETIME: Date and time combination in 'YYYY-MM-DD HH:MM:SS' format.
- TIMESTAMP: Timestamp value, often used for tracking changes to records.
- Boolean Type:
- BOOLEAN: A synonym for TINYINT(1), which can hold true/false, 0/1, or 'Y'/'N' values.
- Binary Types:
- BLOB: Binary Large Object for storing binary data.
- BINARY: Fixed-length binary string.
- VARBINARY: Variable-length binary string.
- Other Types:
- ENUM: A string object that can have only one value, chosen from a list of permitted values.
- SET: A string object that can have zero or more values, chosen from a list of permitted values.
These are the fundamental data types, but there are also variations and extensions based on specific requirements and versions of MySQL.
MySQL String Data Types
In MySQL, a string can hold anything from plain text to binary data such as images or files. Strings can be compared and searched based on pattern matching by using the LIKE operator, regular expression, and full-text search.
Data type | Description | |
1 | CHAR(size) | A FIXED length string (can contain letters, numbers, and special characters). The size parameter specifies the column length in characters - can be from 0 to 255. Default is 1 |
2 | VARCHAR(size) | A VARIABLE length string (can contain letters, numbers, and special characters). The sizeparameter specifies the maximum column length in characters - can be from 0 to 65535 |
3 | BINARY(size) | Equal to CHAR(), but stores binary byte strings. The size parameter specifies the column length in bytes. Default is 1 |
4 | VARBINARY(size) | Equal to VARCHAR(), but stores binary byte strings. The size parameter specifies the maximum column length in bytes. |
5 | TINYBLOB | For BLOBs (Binary Large OBjects). Max length: 255 bytes |
9 | TINYTEXT | Holds a string with a maximum length of 255 characters |
10 | TEXT(size) | Holds a string with a maximum length of 65,535 bytes |
6 | BLOB(size) | For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data |
11 | MEDIUMTEXT | Holds a string with a maximum length of 16,777,215 characters |
7 | MEDIUMBLOB | For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data |
12 | LONGTEXT | Holds a string with a maximum length of 4,294,967,295 characters |
8 | LONGBLOB | For BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data |
13 | ENUM(val1, val2, val3, ...) | A string object that can have only one value, chosen from a list of possible values. You can list up to 65535 values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted. The values are sorted in the order you enter them |
14 | SET(val1, val2, val3, ...) | A string object that can have 0 or more values, chosen from a list of possible values. You can list up to 64 values in a SET list |
Numeric Data Types
In MySQL, you can find all SQL standard numeric types including exact number data types, and approximate numeric data types including integer, fixed-point, and floating-point. In addition, MySQL also has BIT data type for storing bit values. Numeric types can be signed or unsigned except for the BIT type. The following table shows the summary of numeric types in MySQL:
Data type | Description | |
BIT(size) | A bit-value type. The number of bits per value is specified in size. The sizeparameter can hold a value from 1 to 64. The default value for size is 1. | |
TINYINT(size) | A very small integer. Signed range is from -128 to 127. Unsigned range is from 0 to 255. The size parameter specifies the maximum display width (which is 255) | |
BOOL | Zero is considered as false, nonzero values are considered as true. | |
BOOLEAN | Equal to BOOL | |
SMALLINT(size) | A small integer. Signed range is from -32768 to 32767. Unsigned range is from 0 to 65535. The size parameter specifies the maximum display width (which is 255) | |
MEDIUMINT(size) | A medium integer. Signed range is from -8388608 to 8388607. Unsigned range is from 0 to 16777215. The size parameter specifies the maximum display width (which is 255) | |
INT(size) | A medium integer. Signed range is from -2147483648 to 2147483647. Unsigned range is from 0 to 4294967295. The size parameter specifies the maximum display width (which is 255) | |
INTEGER(size) | Equal to INT(size) | |
BIGINT(size) | A large integer. Signed range is from -9223372036854775808 to 9223372036854775807. Unsigned range is from 0 to 18446744073709551615. The size parameter specifies the maximum display width (which is 255) | |
FLOAT(size, d) | A floating point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter. This syntax is deprecated in MySQL 8.0.17, and it will be removed in future MySQL versions | |
FLOAT(p) | A floating point number. MySQL uses the p value to determine whether to use FLOAT or DOUBLE for the resulting data type. If p is from 0 to 24, the data type becomes FLOAT(). If p is from 25 to 53, the data type becomes DOUBLE() | |
DOUBLE(size, d) | A normal-size floating point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the dparameter | |
DOUBLE PRECISION(size, d) | ||
DECIMAL(size, d) | An exact fixed-point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter. The maximum number for size is 65. The maximum number for d is 30. The default value for size is 10. The default value for d is 0. | |
DEC(size, d) | Equal to DECIMAL(size,d) |
Date and Time Data Types
MySQL provides types for date and time as well as the combination of date and time. In addition, MySQL supports the timestamp data type for tracking the changes in a row of a table. If you just want to store years without dates and months, you can use the YEAR data type.
The following table illustrates the MySQL date and time data types:
Data type | Description |
DATE | A date. Format: YYYY-MM-DD. The supported range is from '1000-01-01' to '9999-12-31' |
DATETIME(fsp) | A date and time combination. Format: YYYY-MM-DD hh:mm:ss. The supported range is from '1000-01-01 00:00:00' to '9999-12-31 23:59:59'. Adding DEFAULT and ON UPDATE in the column definition to get automatic initialization and updating to the current date and time |
TIMESTAMP(fsp) | A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch ('1970-01-01 00:00:00' UTC). Format: YYYY-MM-DD hh:mm:ss. The supported range is from '1970-01-01 00:00:01' UTC to '2038-01-09 03:14:07' UTC. Automatic initialization and updating to the current date and time can be specified using DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP in the column definition |
TIME(fsp) | A time. Format: hh:mm:ss. The supported range is from '-838:59:59' to '838:59:59' |
YEAR | A year in four-digit format. Values allowed in four-digit format: 1901 to 2155, and 0000.MySQL 8.0 does not support year in two-digit format. |
Boolean Data Type
MySQL does not have the built-in BOOLEAN or BOOL data type. To represent boolean values, MySQL uses the smallest integer type which is TINYINT(1). In other words, BOOLEAN and BOOL are synonyms for TINYINT(1).