Mysql zerofill length different from default field length

Question

I am using MySQL and InnoDB.

I need to store a numeric id which length can vary but needs to be at least 10. For instance:
0000000001
11111111111 are both correct values.

Currently, I my column has the following attributes: bigint(10), unsigned zerofill. This works: if I try to insert "1" then "0000000001" is actually inserted, and if I insert a bigger number (with length>10) it also works.

So, in the end, what is the purpose of the length attribute in the field definition? I thought it was the maximum length, but apparently it is not the case...? Or is my current implementation going to crash eventually?

Look at this: http://stackoverflow.com/questions/5634104/what-is-the-size-of-column-of-int11-in-mysql-in-bytes — Shoaib Shakeel, Apr 10 '15 at 10:18

score 0 · Accepted Answer · answered Apr 10 '15 at 10:05

The length attribute is just a hint for MySQL how to format select query results in the command line client. Nothing more. It has no effect on the datatype actually. An int is an int with 4 bytes, no matter what length you specify. Same of course for bigint, but with 8 bytes.

Mysql zerofill length different from default field length

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