MySQL database design, among which, for data performance optimization, the consideration of field types is very important. I collected some information and organized and shared it. This is the syntax introduction about mysql integer types bigint, int, mediumint, smallint and tinyint, as follows:
1. bigint
Integer data (all numbers) from -2^63 (-9223372036854775808) to 2^63-1 (9223372036854775807), unsigned in the range 0 to
18446744073709551615. One bit is 8 bytes.
2、int
A normal-sized integer. Signed range is -2^31 (-2,147,483,648) to 2^31 - 1 (2,147,483,647) integer data (all numbers), unsigned range is 0 to 4294967295. One bit is 4 bytes in size. The SQL-92 synonym for
int is integer .
3. mediumint is
a medium-sized integer with a signed range of -8388608 to 8388607 and an unsigned range of 0 to 16777215. One bit is 3 bytes in size.
4、smallint
a small integer. Signed range is -2^15 (-32,768) to 2^15 - 1 (32,767) integer data, unsigned range is 0 to 65535. One bit is 2 bytes in size. MySQL provides more than enough features, and since MySQL is open source software, it can greatly reduce the total cost of ownership.
5、tinyint
The signed range is -128 - 127, and the unsigned range is integer data from 0 to 255. One bit is 1 byte in size.
Note that all arithmetic operations are done with signed BIGINT or DOUBLE values, so you should never use signed big integers larger than 9223372036854775807 (63 bits), except for bit functions! Note that -, + and * will use the BIGINT operation when both arguments are INTEGER values! This means that if you multiply 2 large integers (or from a function that returns an integer), you can get unexpected results if the result is greater than 9223372036854775807. A floating-point number, which cannot be unsigned, can be <= 24 for a single-precision floating-point number, and between 25 and 53 for a double-precision floating-point number. These types such as FLOAT and DOUBLE are immediately Described below. FLOAT(X) has the same range as FLOAT and DOUBLE, but the display size and scale are undefined. In MySQL 3.23, this is a true floating point value. In earlier MySQL versions, FLOAT(precision) always had 2 decimal places. This syntax is provided for ODBC compatibility.
The range of
TINYINT
-128 - 127
TINYINT UNSIGNED
0 - 255
SMALLINT
-32768 - 32767
SMALLINT UNSIGNED
0 - 65535
MEDIUMINT
-8388608 - 8388607
MEDIUMINT UNSIGNED
0 - 16777215 INT
or INTEGER
-2147483648
UNSIGNED
0 - 4294967295
BIGINT
-9223372036854775808 - 9223372036854775807
BIGINT UNSIGNED
0 - 18446744073709551615
FLOAT
-3.402823466E + 38 is - 38,0,1.175494351E--1.175494351E-38 is - 3.402823466E + 38 is
DOUBLE or DOUBLE PRECISION or REAL
-1.7976931348623157E+308 - -2.2250738585072014E-308,0,2.2250738585072014E-308 - 1.7976931348623157E+308
DECIMAL[(M,[D])] or NUMERIC(M,D)
length of the whole number, including the decimal point by M( , the number of digits to the left of the decimal point, the number of digits to the right of the decimal point, but not including the negative sign) and D (the number of digits to the right of the decimal point) to decide, M defaults to 10, D defaults to 0
DATE
1000-01-01 - 9999 -12-31
DATETIME
1000-01-01 00:00:00 - 9999-12-31 23:59:59
TIMESTAMP
1970-01-01 00:00:00 - a day in 2037 I don't know, huh)
TIME
-838:59:59' to 838:59:59
YEAR[(2|4)]
The default is 4-bit format, the value range of 4-bit format is 1901 - 2155,0000, 2-bit format The value range is 70-69 (1970-2069)
CHAR(M) [BINARY] or NCHAR(M) [BINARY]
The range of M is 1 - 255. If there is no BINARY item, it is case-insensitive. The provincial character set. Filled with spaces in the database, but trailing spaces will be automatically removed when fetched.
[NATIONAL] VARCHAR(M) [BINARY]
The range of M is 1 - 255. Trailing spaces will be automatically removed in the database remove.
TINYBLOB or TINYTEXT
255 (2^8-1) characters
BLOB or TEXT
65535 (2^16-1) characters
MEDIUMBLOB or MEDIUMTEXT
16777215 (2^24-1) characters
LONGBLOB or LONGTEXT
4294967295 (2^32-1) characters
ENUM('value1','value2',...)
can have a total of 65535 distinct values
SET('value1','value2',...)
has a maximum of 64 members
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AfrikaansAlbanianArabicArmenianAzerbaijaniBasqueBelarusianBengaliBosnianBulgarianCatalanCebuanoChichewaChinese (Simplified)Chinese (Traditional)CroatianCzechDanishDutchEnglishEsperantoEstonianFilipinoFinnishFrenchGalicianGeorgianGermanGreekGujaratiHaitian CreoleHausaHebrewHindiHmongHungarianIcelandicIgboIndonesianIrishItalianJapaneseJavaneseKannadaKazakhKhmerKoreanLaoLatinLatvianLithuanianMacedonianMalagasyMalayMalayalamMalteseMaoriMarathiMongolianMyanmar (Burmese)NepaliNorwegianPersianPolishPortuguesePunjabiRomanianRussianSerbianSesothoSinhalaSlovakSlovenianSomaliSpanishSundaneseSwahiliSwedishTajikTamilTeluguThaiTurkishUkrainianUrduUzbekVietnameseWelshYiddishYorubaZulu |
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