MySQL Learning note five: data types

MySQL supports a variety of data types, which can be roughly divided into numeric values, date/time, and character types.

Numeric type

MySQL supports all standard SQL numeric data types, including strict numeric data types (INTEGER, SMALLINT, Decimal, and numeric), and approximate numeric data types (FLOAT, real, and double PRECISION). In addition to these, tinyint, mediumint and bigint are supported. The occupied bytes and ranges of these types are as follows.

type	size	Range (signed)	Range (unsigned)	Use
TINYINT	1 bytes	(-128,127)	(0,255)	Small integer value
SMALLINT	2 bytes	(-32 768,32 767)	(0,65 535)	Large integer value
Mediumint	3 bytes	(-8 388 608,8 388 607)	(0,16 777 215)	Large integer value
int or integer	4 bytes	(-2 147 483 648,2 147 483 647)	(0,4 294 967 295)	Large integer value
BIGINT	8 bytes	(-9 233 372 036 854 775 808,9 223 372 036 854 775 807)	(0,18 446 744 073 709 551 615)	Maximum integer value
FLOAT	4 bytes	( -3.402 823 466 e+38,1.175 494 351 E-38), 0, (1.175 494 351 e-38,3.402 823 466 351 e+38)	0, (1.175 494 351 e-38,3.402 823 466 e+38)	Single precision Floating point value
DOUBLE	8 bytes	(1.797 693 134 862 315 7 e+308,2.225 073 858 507 201 4 E-308), 0, (2.225 073 858 507 201 4 e-308,1.797 693 134 862 315 7 e+3 08)	0, (2.225 073 858 507 201 4 e-308,1.797 693 134 862 315 7 e+308)	Double precision Floating point value
DECIMAL	For decimal (m,d), if m>d, is m+2 otherwise d+2	Values that depend on M and D	Values that depend on M and D	Decimal value

Date and Time type

The

includes datetime, DATE, TIMESTAMP, Time, and year, each with a valid range of values and a value of "0", using the "0" value when specifying an illegal MySQL value that cannot be represented.

type	size (bytes)	Range	format	Use
DATE	3	1000-01-01/9999-12-31	Yyyy-mm-dd	Date value
Time	3	' -838:59:59 '/' 838:59:59 '	HH:MM:SS	Time Value or duration
Year	1	1901/2155	YYYY	Year value
Datetime	8	1000-01-01 00:00:00/9999-12-31 23:59:59	YYYY-MM-DD HH:MM:SS	Blend date and time values
TIMESTAMP	8	1970-01-01 00:00:00/2037, sometime	YYYYMMDD HHMMSS	Mixed date and time values, timestamp

Character type

The

String type refers to Char, VARCHAR, BINARY, VARBINARY, BLOB, TEXT, enum, and set.

type	size	purpose
CHAR	0-255-byte	fixed-length string
VARCHAR	0-255-byte	variable-length string
tinyblob	0-255-byte	no more than 255-character binary string
Tinytext	0-255 bytes	short text string
BLOB	0-65 535 bytes	long text data in binary form
text	0-65 535 bytes	long text data
mediumblob	0-16 777 215 bytes	binary Form medium-length text data
mediumtext	0-16 777 215 bytes	medium-length text data
logngblob	0-4 294 967 295 bytes	binary form of large text data
longtext	0-4 294 967 295 bytes	Extreme Text data

Char differs from varchar: save and process, trailing spaces are retained. Char is suitable for fields with definite length, while varchar is the opposite, char is generally faster than varchar, but it wastes space and reduces storage efficiency.

MySQL Learning note five: data types