How to get last 12 digits from a string in MySQL?

How would I get last 12 digits of a string using mysql?

Let's say I have a varchar field with a tracking number, that may be anywhere from 5 to 20 varchars long. But I only need to select last 12 digits or less if there are less.

so in a field = 12345678123456789012

I would only need to get what's in brackets

field = 12345678[123456789012]

I saw a few examples开发者_JAVA技巧 using mid, etc, but they dont' produce the desired result or I can't find an example that makes sense :-(

Thank you.

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SELECT RIGHT(field, 12);

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Nick,

Try using the RIGHT(str, len) function.

http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_right

I'm not sure of the semantics if the string is shorter than length as I don't have access to MySQL but it might do what you're looking for.