Data type confusion: what is an int (11 )?, Confusionint

Data type confusion: what is an int (11 )?, Confusionint

Http://everythingmysql.ning.com/profiles/blogs/data-type-confusion-what-is-an

 

Over and over I see MERs that don't understand whatint(11)Really means. Their confusion is understandable. Unknown know what definingchar(10)Means (a fixed-sized character string that allows up to 10 characters). However, ints are different.

First of all, there are 5 types of integer. They are all fixed size.

Type	# Of bytes
Tinyint	1
Smallint	2
Mediumint	3
Int	4
Bigint	8

As you can see from the chart,intIsAlways4 bytes. That can store signed numbers from-2 billion to + 2 billion (and unsigned numbers 0 to 4B). So, what does it mean if you declareint(5)? It does not restrict the number of digits to 5... It may be actually do nothing! The (5) part is a display width. it's only used if you use UNSIGNED and ZEROFILL with an integer type. then the display of those numbers will be zero-padded on the left to 5 digits if they contain less than 5 digits. example:


CREATE TABLE `foo` (
`bar` int(5) unsigned zerofill DEFAULT NULL
)


 SELECT * FROM foo;+---------+
| bar     |
+---------+
|   00042 | 
|   00101 | 
| 9876543 | 
+---------+