Differences in integer data in MySQL

bigint
Integer data (all numbers) from -2^63 (-9223372036854775808) to 2^63-1 (9223372036854775807). The storage size is 8 bytes.
P.S. bigint already has length, in MySQL build table length, just used to display the number of bits, general bigint (20), this width and bigint the value of the size independent, just for display. because the display width of the integer type has no effect on the numerical size, it is only when the Zerofill is set, it is 0 when it is displayed.
int
Integer data (all numbers) from -2^31 (-2,147,483,648) to 2^31–1 (2,147,483,647). The storage size is 4 bytes. The SQL-92 synonymous word for int is integer. General Int (one)
smallint
Integer data from -2^15 (-32,768) to 2^15–1 (32,767). The storage size is 2 bytes. General smallint (6)

Mediumint

Range ( -8388608~8388607) with a storage size of 3 bytes. General Mediumint (8)
tinyint
Integer data from 0 to 255. The storage size is 1 bytes. General tinyint (4)
Notes
Support for bigint data types where integer values are supported. However, bigint is used in some special cases when the integer value exceeds the range supported by the INT data type, bigint can be used. In SQL Server, the int data type is the primary integer data type.
In the data type precedence table, bigint is located between smallmoney and Int.
The function returns bigint only if the parameter expression is a bigint data type. SQL Server does not automatically promote other integer data types (tinyint, smallint, and int) to bigint.
Int (m) in the integer data type, m represents the maximum display width. in int (m), the value of M is not related to how much storage space the Int (m) occupies. and the number of digits is also not related to int (3), int (4), int (8) on disk, which occupies 4 btyes of storage space.

Differences in integer data in MySQL