区别在于分配给每个整数的内存数量，以及它们各自可以存储多大的数字。

所需存储空间的大小以及数字的大小。

SQL Server:

Tinyint 1字节，0 ~ 255 Smallint 2字节，-215(-32,768)到215-1 (32,767) Int 4字节，-231(- 2147,483,648)到231-1 (2147,483,647) Bigint 8字节，-263(-9,223,372,036,854,775,808)到263-1 (9,223,372,036,854,775,807)

你可以将数字1存储在所有4个字节中，但是bigint将使用8个字节，而tinyint将使用1个字节。

这些似乎是MySQL数据类型。

根据他们拿到的文件:

Tinyint = 1字节 Smallint = 2字节 Mediumint = 3字节 Int = 4字节 Bigint = 8字节

并且，自然地，接受越来越大范围的数字。

数据类型范围存储

bigint  -2^63 (-9,223,372,036,854,775,808) to 2^63-1 (9,223,372,036,854,775,807)    8 Bytes
int -2^31 (-2,147,483,648) to 2^31-1 (2,147,483,647)    4 Bytes
smallint    -2^15 (-32,768) to 2^15-1 (32,767)  2 Bytes
tinyint 0 to 255    1 Byte

例子

下面的示例使用bigint、int、smallint和tinyint数据类型创建一个表。值被插入到每一列中，并在SELECT语句中返回。

CREATE TABLE dbo.MyTable
(
  MyBigIntColumn bigint
 ,MyIntColumn  int
 ,MySmallIntColumn smallint
 ,MyTinyIntColumn tinyint
);

GO

INSERT INTO dbo.MyTable VALUES (9223372036854775807, 214483647,32767,255);
 GO
SELECT MyBigIntColumn, MyIntColumn, MySmallIntColumn, MyTinyIntColumn
FROM dbo.MyTable;

When it gets to real world usage of these datatypes, it is very important that you understand that using certain integer types could just be an overkill or under used. For example, using integer datatype for employeeCount in a table say employee could be an overkill since it supports a range of integer values from ~ negative 2 billion to positive 2 billion or zero to approximately 4 billion (unsigned). So, even if you consider one of the US biggest employer such as Walmart with roughly about 2.2 million employees using an integer datatype for the employeeCount column would be unnecessary. In such a case you use mediumint (that supports from 0 to 16 million (unsigned)) for example. Having said that if your range is expected to be unusually large you might consider bigint which as you can see from Daniel's notes supports a range larger than I care to decipher.

区别在于分配给每个整数的内存数量，以及它们各自可以存储多大的数字。