MySQL INTの意味

Question

INTの値を8にしても、1から99999999まで、または1から4294967295のUNSIGNEDしか使用できないのでしょうか？

Answer 1

ドキュメントには、このことについて、かなり明確なようだ：

数値型は

MySQLは、必要に応じて基本キーワードに続く括弧内の整数データ型のディスプレイ 幅を指定するための拡張機能をサポートしています属性タイプの場合は です。たとえば、INT（4）は、ディスプレイ の幅4桁のINTを指定します。このオプションの表示幅は、 アプリケーションで、列に指定された幅が より小さい整数値をスペースで左に埋めて表示するために使用されます。表示幅が を格納することができる値の範囲を制限しない

（ この幅は、結果セットで返されたメタデータに存在する、である。それが使用されるかどうか かはアプリケーション次第である。ように）列にまた、列幅 の幅よりも広い値が正しく表示されないこともありません。たとえば、SMALLINT（3）として指定された列 は、通常のSMALLINT範囲が-32768〜 32767であり、3桁で許可された範囲外の値は、3桁を超えてフルで表示される です。

http://dev.mysql.com/doc/refman/5.5/en/numeric-types.html

Answer 2

mysql documentationをご覧ください。すべてのデータ型の詳細を知ることができます。符号なしの場合、最大値は4294967295です。

Answer 3

明示的に符号なし整数を選択する必要があります。符号付き整数で、デフォルトでは符号付き整数であるため、ネガも使用できます。 Tom Squiresが提供するリンクのドキュメントを見てください。

ところで、私が見つけたものを見 - > *のhttp：//help.scibit.com/mascon/masconMySQL_Field_Types.html*

Type 
Use for 
Size 
TINYINT 
A very small integer 
The signed range is –128 to 127. The unsigned range is 0 to 255. 
SMALLINT 
A small integer 
The signed range is –32768 to 32767. The unsigned range is 0 to 65535 
MEDIUMINT 
A medium-size integer 
The signed range is –8388608 to 8388607. The unsigned range is 0 to 16777215 
INT or INTEGER 
A normal-size integer 
The signed range is –2147483648 to 2147483647. The unsigned range is 0 to 4294967295 
BIGINT 
A large integer 
The signed range is –9223372036854775808 to 9223372036854775807. The unsigned range is 0 to 18446744073709551615 
FLOAT 
A small (single-precision) floating-point number. Cannot be unsigned 
Ranges are –3.402823466E+38 to –1.175494351E-38, 0 and 1.175494351E-38 to 3.402823466E+38. If the number of Decimals is not set or <= 24 it is a single-precision floating point number 
DOUBLE, 
DOUBLE PRECISION, 
REAL 
A normal-size (double-precision) floating-point number. Cannot be unsigned 
Ranges are -1.7976931348623157E+308 to -2.2250738585072014E-308, 0 and 2.2250738585072014E-308 to 1.7976931348623157E+308. If the number of Decimals is not set or 25 <= Decimals <= 53 stands for a double-precision floating point number 
DECIMAL, 
NUMERIC 
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 Length. If Decimals 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 Length and Decimals. If Decimals is left out it’s set to 0. If Length is left out it’s set to 10. Note that in MySQL 3.22 the Length includes the sign and the decimal point 
DATE 
A date 
The supported range is ‘1000-01-01’ to ‘9999-12-31’. MySQL displays DATE values in ‘YYYY-MM-DD’ format 
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 
TIMESTAMP 
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 
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 
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.) 
CHAR 
A fixed-length string that is always right-padded with spaces to the specified length when stored 
The range of Length 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 
VARCHAR 
A variable-length string. Note: Trailing spaces are removed when the value is stored (this differs from the ANSI SQL specification) 
The range of Length is 1 to 255 characters. VARCHAR values are sorted and compared in case-insensitive fashion unless the BINARY keyword is given 
TINYBLOB, 
TINYTEXT 

A BLOB or TEXT column with a maximum length of 255 (2^8 - 1) characters 
BLOB, 
TEXT 

A BLOB or TEXT column with a maximum length of 65535 (2^16 - 1) characters 
MEDIUMBLOB, 
MEDIUMTEXT 

A BLOB or TEXT column with a maximum length of 16777215 (2^24 - 1) characters 
LONGBLOB, 
LONGTEXT 

A BLOB or TEXT column with a maximum length of 4294967295 (2^32 - 1) characters 
ENUM 
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 
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 

Answer 4

がdocumentationで行く、INT(8)はあなたが表示幅を設定することを意味し

表示幅は、列に格納できる値の範囲を制限しません。また、列の表示幅よりも広い値が正しく表示されないこともありません。