Storing leading zeros of integers in MySQL database as INTEGER

Question

I need MySQL to store numbers in a integer field and maintain leading zeros. I cannot use the zerofill option as my current field is Bigint(16) and numbers can vary in amount of leading zeros. IE: 0001 - 0005, then 008 - 010 may need to be stored. I am not concerned about uniqueness of numbers (these aren't being used as IDs or anything) but I still need them to be stored preferably as INTS.

The issue using CHAR/VARCHAR and then typecasting the values as integers in PHP means that sorting results via queries leads to alphanumeric sorting, IE: SORT BY number ASC would produce

001
002
003
1
100
101
102
2

Clearly not in numerical order, but in alphanumeric order, which isn't wanted.

Hoping for some clever workarounds :)

Solution 1

Keep the numbers stored as integers.

Then use function LPAD() to show the numbers (left) padded with zeros:

SELECT LPAD( 14, 7, '0') AS padded;

| padded  |
-----------
| 0000014 |

If the number of zerofill characters is variable, add another column in the table with that (zerofill) length.

Solution 2

Change the structure of the field and make the Attributes UNSIGNED_ZEROFILL to keep the zeros.

But you should be careful to the Length of the field, because it's gonna return all the rest numbers to zeros so put the length of your field

Solution 3

You can still sort the string(CHAR/VARCHAR) columns like integer using CAST

ORDER BY CAST(`col_name` AS SIGNED) DESC

So, you can store them in CHAR/ VARCHAR type fields.

Solution 4

You can not store integer with leading zeroes. One way is keeping it in varchar as well as int columns. In this case, you need two columns, one value and the other intValue and while sorting, you can use the intValue for sorting. This is easy to implement.

Select Value from Table order by intValue;

The other option can be using two columns, one valu and othe NumOfZero and use these for the desired results. This is complex, but might be light on the DB.

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Comments

[Damien_The_Unbeliever]

integers don't have leading zeroes. Only string representations of them can. So if you "need" leading zeroes, you'll have to store a string representation. Why can't you do this kind of formatting at display time, rather than putting it in the database?

[ZygD]

1 and 001 and different values. But as int they are the same: how should these be sorted and compared? as int or as varchar?

[Aaron W.]

Could also do ORDER BY col_name + 0 DESC to sort a varchar like integer

[Isaiah Turner]

Note: if you know that the column will always be the same length, use CHAR, not VARCHAR.

[Manuel Jordan]

Even when I can confirm that your query works, I have a doubt, Does exist an impact about performance when lpad is used for numeric types? It because lpad is a string-function. Consider the scenario about having a query retrieving a lot of records and ldap is used to format the output of a numeric type.