I'm trying to emulate a function in SQL that a client has produced in Excel. In effect, they have a unique, 10-digit numeric value (VARCHAR) as the primary key in one of their enterprise database systems. Within another database, they require a unique, 5-digit alphanumeric identifier. They want that 5-digit alphanumeric value to be a representation of the 10-digit number. So what they did in excel was to split the 10-digit number into pairs, then convert each of those pairs into a hexadecimal value, then stitch them back together.
The EXCEL equation is:
=IF(VALUE(MID(A2,1,4))>0,DEC2HEX(VALUE(MID(A2,3,2)))&DEC2HEX(VALUE(MID(A2,5,2)))&DEC2HEX(VALUE(MID(A2,7,2)))&DEC2HEX(VALUE(MID(A2,9,2))),DEC2HEX(VALUE(MID(A2,5,2)))&DEC2HEX(VALUE(MID(A2,7,2)))&DEC2HEX((VALUE(MID(A2,9,2)))))
I need the SQL equivalent of this. Of course, should someone out there know a better way to accomplish their goal of "a 5-digit alphanumeric identifier" based off the 10-digit number, I'm all ears.
ADDED 8/2/2011
First of all, thank you to everyone for the replies. Nice to see folks willing to help and even enjoying it! Based on all the responses, I'm apt to tell my client they're intent is sound, only their method is off kilter. I'd also like to recommend a solution. So the challenge remains, just modified slightly:
CHALLENGE: Within SQL, take a 10 digit, unique NUMERIC string and represent it ALPHANUMERICALLY in as few characters as possible. The resulting string must also be unique.
Note that the first 3-4 characters in the 10-digit string are likely to be zeros, and that they could be stripped to shorten the resulting alphanumeric string. Not required, but perhaps helpful.
This problem is inherently impossible. You have a 10 digit numeric value that you want to convert to a 5 digit alphanumeric value. Since there are 10 numeric characters, this means that there are 10^10 = 10 000 000 000 unique values for your 10 digit number. Since there are 36 alphanumeric characters (26 letters + 10 numbers), there are 36^5 = 60 466 176 unique values for your 5 digit number. You cannot map a set of 10 billion elements into a set with around 60 million.
Now, lets take a closer look at what your client's code is doing:
So what they did in excel was to split the 10-digit number into pairs, then convert each of those pairs into a hexadecimal value, then stitch them back together.
This isn't 100% accurate. The excel code never uses the first 2 digits, but performs this operation on the remaining 8. There are two main problems with this algorithm which may not be intuitively obvious:
Two 10 digit numbers can map to the same 5 digit number. Consider the numbers 1000000117 and 1000001701. The last four digits of 1000000117 get mapped to 1 11, where the last four digits of 1000001701 get mapped to 11 1. This causes both to map to 00111.
The 5 digit number may not even end up being 5 digits! For example, 1000001616 gets mapped to 001010.
So, what is a possible solution? Well, if you don't care if that 5 digit number is unique or not, in MySQL you can use something like:
hex(<NUMERIC VALUE> % 0xFFFFF)
The log of 10^10 base 2 is 33.219280948874
> return math.log(10 ^ 10) / math.log(2)
33.219280948874
> = 2 ^ 33.21928
9999993422.9114
So, it takes 34 bits to represent this number. In hex this will take 34/4 = 8.5 characters, much more than 5.
> return math.log(10 ^ 10) / math.log(16)
8.3048202372184
The Excel macro is ignoring the first 4 (or 6) characters of the 10 character string.
You could try encoding in base 36 instead of 16. This will get you to 7 characters or less.
> return math.log(10 ^ 10) / math.log(36)
6.4254860446923
The popular base 64 encoding will get you to 6 characters
> return math.log(10 ^ 10) / math.log(64)
5.5365468248123
Even Ascii85 encoding won't get you down to 5.
> return math.log(10 ^ 10) / math.log(85)
5.1829075929158
You need base 100 to get to 5 characters
> return math.log(10 ^ 10) / math.log(100)
5
There aren't 100 printable ASCII characters, so this is not going to work, as zkhr explained as well, unless you're willing to go beyond ASCII.
I found your question interesting (although I don't claim to know the answer) - I googled a bit for you out of interest and found this which may help you http://dpatrickcaldwell.blogspot.com/2009/05/converting-decimal-to-hexadecimal-with.html
Related
I have a column with numbers with various lengths such as 50055, 1055,155 etc. How can I add a decimal before the last 2nd place of each so that it would be 500.55, 10.55, and 1.55?
I tried using replace by finding the last 2 numbers and replace it with .||last 2 number. That doesn't always work because of a possibility of multiple repetition of the same sequence in the same string.
replace(round(v_num/2),substr(round(v_num/2),-2),'.'||substr(round(v_num/2),-2))
You would divide by 100:
select v_num / 100
You can convert this into a string, if you want.
I have input comprising five character upper-case English letters e.g ABCDE and I need to convert this into two character unique ASCII output.
e.g. ABCDE and ZZZZZ should both give two different outputs
I have converted from ABCDE into hex which gives me 4142434445, but from this can I get to a two character output value I require?
Example:
INPUT1 = ABCDE
Converted to hex = 4142434445
INPUT2 = 4142434445
OUTPUT = ?? Any 2 ASCII Characters
Other examples of INPUT1 =
BIRAL
BRMAL
KLAAX
So you're starting with a 5-digit base-26 number, and you want to squeeze that into some 2-digit scheme with base n?
All possible 1-5 digit base-26 numbers gives you a number space of 26^5 = 11,881,376.
So you want the minimum n where n^2 >= 11,881,376.
Which gives you 3446.
Now it's up to you to go and find a suitable glyph block somewhere in UTF where you can reliably block-out 3446 separate characters to act as your new base/alphabet. And construct a mapping from your 5-char base-26 ABCDE type number onto your 2-char base-3446 wierd-glyph number. Good luck with that.
There's not enough variety in ASCII to do this, since it's only 128 printable characters. Limiting yourself to 2-chars of ASCII means you can only address a number space of 16384.
Currently I have a table with the following format/Desc:
ColumnName ColID PK IndexPos Null DataType
ID 1 1 N VARCHAR2 (1 Byte)
FILEPATH 2 N VARCHAR2 (127 Byte)
As you can see the length of ID Column is only 1 Byte we can store only 36 different file paths. I have more than 35 different file paths that has to be stored and retrieved. I know increasing the length of ID solves the issue but I want to also know/suggestion that is there any Efficient way to handle this.
Thanks!
The assertion that you can store only 35 different values in the table is incorrect, because varchar2 characters are not limited to letters and digits (even if they were you'd have 26 letters + 10 digits + 1 empty string = 37, not 35 possibilities).
If you need to store few more paths, say, 40 or 50, you could make your keys mixed case, so 'a' and 'A' would reference different paths. This would instantly give you 26 extra possibilities.
Expanding past the limit of 63 is a little harder, because you need to bring special characters into the mix. However, the theoretical maximum for a single character is 256 plus one combination for an empty string.
I'm trying to write a query in oracle sql to get rows which has invalid 10 digit numbers, ie with other symbols in between them.
For example:
(111) 111-1111 #10 digit number with some symbols and spaces in between
111-111-1111
(111)111-1111
111)111-1111
(111) 11 1-1111
ie, It should match exactly 10 digit numbers which are non consecutive because it has some symbols in it.
So it should not match the following example:
111 #consecutive 3 digit number
11 1 #3 digit number with spaces
11-1 #3 digit number with symbol in between
1111111111 #consective 10 digit number
And I'm using REGEXP_LIKE, something like this
select * from table where REGEXP_LIKE(column, ?)
Any help is much appreciated. Thanks.
You could use a combination of a regex and length; the latter to exclude a pure 10-digit number without other characters:
regexp_like(col, '^[ .()-]*(\d[ .()-]*){10}$') and length(col) > 10
In the [.()-] class you would list all the characters that you would allow as symbols among the digits. Note that - needs to be the last in that list or else be escaped.
If you would allow any non-digit to occur among the 10 digits, you can use \D:
regexp_like(col, '^\D*(\d\D*){10}$') and length(col) > 10
So: the string should have length greater than 10, and the total number of digits must be exactly 10. This can be done without regular expressions (which should make it faster):
... where length(str) > 10 and
length(str) = 10 + length(translate(str, 'z0123456789', 'z'))
translate will translate the letter z to itself and all the other characters (digits) to nothing. Having to include the z is annoying, but unavoidable; translate will return NULL if any of its arguments is NULL. The second condition says the length of the input str is exactly 10 more than the length of the string with all digits removed - so there are exactly 10 digits.
I have a question about the format of numbers REAL.
I have a column with this type and after I insert 8 numbers for this column, it doesn't let me to save.
Example: 11406760
When I try with a 7 digit numbers like 1140676, it lets me to save the data.
Any idea why this happens?
If I read this MSDN page correctly, REAL is a synonym for FLOAT(24), which has a precision of 7 digits.
This means that while a column of this type does support values up to about 10^38, it only keeps about 7 most significant digits of that value. So for an 8 digit number, the final digit may not be stored correctly.
Do you really need a REAL (=floating point) value for this column (maybe check out decimal), or rather some integer type?