Types in MySQL: BigInt(20) vs Int(20)

Question

I was wondering what the difference between BigInt, MediumInt, and Int are... it would seem obvious that they would allow for larger n

Answer 1

Let's give an example for int(10) one with zerofill keyword, one not, the table likes that:

create table tb_test_int_type(
    int_10 int(10),
    int_10_with_zf int(10) zerofill,
    unit int unsigned
);

Let's insert some data:

insert into tb_test_int_type(int_10, int_10_with_zf, unit)
values (123456, 123456,3147483647), (123456, 4294967291,3147483647) 
;

Then

select * from tb_test_int_type; 

# int_10, int_10_with_zf, unit
'123456', '0000123456', '3147483647'
'123456', '4294967291', '3147483647'

We can see that

• with keyword zerofill, num less than 10 will fill 0, but without zerofill it won't

• Secondly with keyword zerofill, int_10_with_zf becomes unsigned int type, if you insert a minus you will get error Out of range value for column...... But you can insert minus to int_10. Also if you insert 4294967291 to int_10 you will get error Out of range value for column.....

Conclusion:

1. int(X) without keyword zerofill, is equal to int range -2147483648~2147483647

2. int(X) with keyword zerofill, the field is equal to unsigned int range 0~4294967295, if num's length is less than X it will fill 0 to the left