 | Thanks to everyone who entered the Obfuscated SQL Contest! This ran on the PL/SQL Challenge from March - April. It asked players to produce ingenious, creative, quirky and downright weird SQL to return the current time in the timezones Bangalore, London, New York, Chicago and Denver. There were 53 entries, many of which provoked serious head scratching amongst the judges to determine how these queries actually work! After much deliberating in an exceptionally close run contest the judges have chosen the following entries as winners: |
Overall winner: Stelios Vlasopoulos
Runner up: Sean Stuber
Runner up: James Su
These entries all fully got into the spirit of the contest producing ingenious and convoluted SQL. Let’s look at these in more detail to see why:
Stelios
A beast of a query that uses a huge number of features, abuses HTTP calls and has convoluted expressions “just because”!
The features used by this query include:
- Model Clause
- Numerous unnecessary, string, number and hex conversions
- With clause
- Multiple regular expressions
- A HTTP call to get the timezone
- XML parsing
- Row generation using "connect by level" and "group by cube"
- Unnecessary calculations
- Cross join
Sean
An ingenious solution with an encrypted SQL string that's decrypted using inline PL/SQL in SQL. Key feature (mis)use:
- HTTP call to get the time
- Inline PL/SQL
- Execute immediate to convert "junk" to real SQL
- XML parsing
- Full outer join
James
An elegantly complex solution that hides the actual SQL statement in a string of spaces!
- A string of spaces and tabs is converted into an actual select statement via string manipulation
- The actual query is executed and converted to XML using DBMS_XMLGEN.getxmltype
All three are brilliant examples of obscure SQL. Congratulations to Stelios, Sean and James!
You can view these entries at the bottom of this post. If you'd like to view all the entries head here. Stay tuned for blog posts dedicated to each of the winners entries, dissecting them in detail to explain how they work.
In addition to the top three, there are several other high quality entries worthy of mention.
Anton Scheffer
A truly convoluted select statement that includes a bucket list of features. In addition to many already mentioned it also includes:
- Analytic functions
- MULTISET operators
- LNNVL
- DBMS_DEBUG_VC2COLL to convert a list to an array
- Calls to DBMS_RANDOM!
With all these features this would be a strong contender for the title. Unfortunately this doesn't always produce the correct output, so lost out for not fully meeting the requirements.
Laurent Schneider
Another devious query using a stack of features. Those not already listed above include:
- JSON manipulation
- Rows generated using SYS.ODCIVARCHAR2LIST
- Different methods of timezone naming
- A recursive inline PL/SQL function
This also failed to meet the requirements. The timezone for Chicago and Denver aren't right, the output is wrong for these places. With some small tweaking this would also be in the running for the top spots.
TonyC
Uses common table expressions (WITH clause) combined with mind bending string manipulation to extract the dates. Key features not highlighted in other solutions:
- Reverses a string with the timezones listed
- Calls WM_CONCAT to convert rows into a string
Thanks again to everyone who took part and helped make this an enjoyable contest. We'll run more of these in future, so stay tuned!
Here are the winning statements:
Stelios' SQL
with d1 as
(
select regexp_substr(z,'[^,]+',1,3*level-2) a,
regexp_substr(z,'[^,]+',1,3*level-1)*power(1e1,-6) b,
regexp_substr(z,'[^,]+',1,3*level)*(case when mod(3*level,3)=0 and rownum > 1 then -1 else 1 end)* power(1e1,-6) c
from (
select to_char(regexp_substr (x.a,'\d{23}',1,rn),'FM999999G99999999G999999999', 'NLS_NUMERIC_CHARACTERS=.,') z
from (
select
utl_raw.cast_to_varchar2(utl_raw.bit_xor(hextoraw('5B4F5D504E3831323939323337393037373638313239373736373937383531353130333537303030313136373733373836393837343037383530393130373339363832383536373732373334313838313833323038373632333137373638363937383339373432303433313034393931353331'),hextoraw(trim(to_char(470188516729,'XXXXXXXXXX'))))) a
from dual
) x
cross join (select rownum rn from (select 1 num from dual group by cube (1,2,3)) where rownum<=sqrt(25))) y
connect by level <= (length(regexp_replace(z,'[^,]+')) + 3)/3
),
d2 as
(select ct, x, y from d1
model
partition by (rownum rn)
dimension by (0 dim)
measures (cast( a as varchar2(65)) as ct, a, cast(b as varchar2(30)) as x, b, cast(c as varchar2(30)) as y, c)
rules upsert iterate (3)
(
ct[0]=(case when iteration_number = 0 then null else ct[0] end )||
chr(regexp_substr(a[0],'\d{2}',1,iteration_number+1)),
x[0]=rawtohex(to_char(b[0])),y[0]=rawtohex(to_char(c[0]))
)
order by rn
)
select
rtrim(xmltransform
(sys_xmlagg(sys_xmlgen(new_time)),
xmltype
('<?xml version="1.0"?><xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"><xsl:template match="/"><xsl:for-each select="/ROWSET/NEW_TIME"><xsl:value-of select="text()"/>; </xsl:for-each></xsl:template></xsl:stylesheet>'
)
).getstringval(),'; ') timezones
from
(
select ct ||' - '||to_char(current_timestamp at time zone tz,'DD-MON-YYYY HH24:MI:SS') new_time
from
(
select z.ct, p.column_value.extract('//text()').getstringval() as tz
from
(select d2.ct,
httpuritype(utl_raw.cast_to_varchar2(hextoraw('687474703A2F2F687474703A2F2F77732E67656F6E616D65732E6F72672F74696D657A6F6E653F6C61743D'
||d2.x||'266C6E673D'||d2.y||'26757365726E616D653D73766C61323939'))).getxml() req
from d2
) z, table(xmlSequence(z.req.extract(utl_raw.cast_to_varchar2(hextoraw('2F67656F6E616D65732F74696D657A6F6E652F74696D657A6F6E654964'))))) p
)
)
/Sean's SQL
--Requires 12c to implement function in WITH clause.
--Must be run as SYS or SYSTEM and database server must have access to internet
--The internet call is safe, but please do reverse engineer the text to evaluate the inner workings.
WITH FUNCTION s
RETURN VARCHAR2
IS
s VARCHAR2(1000);
BEGIN
EXECUTE IMMEDIATE TRANSLATE(
q'{HVKW
pu
M:.*6-:, on< +1 63/4:3:2+ 9*2<+612 62 HVKW <4>*,:q
R*,+ =: -*2 >, LFL 1- LFLKZR 62 1-;:- +1 >)16; 2::;628 > 2:+(1-5 _]S ;:962:;q
K76, 3>5:, 21 <>44, +1 LFL[_KZs LFLKVRZLK_ROs ]JMMZQKA[_KZ 1- ]JMMZQKAKVRZLK_RO +1 -:+-6:): +7: +63:
V2,+:>; +7: <*--:2+ +63: 6, /*44:; 9-13 +7: JL Q>)>4 P=,:-)>+1-%x, >+136< <41<5
up
YJQ]KVPQ 1n6w/ VQ I_M]W_Mnv
MZKJMQ VQKZMI_S [_F KP LZ]PQ[
_L
- VQKZMI_S [_F KP LZ]PQ[d
, VQKZXZM eb ]_LZ HWZQ / SVTZ xryx KWZQ ro ZSLZ o ZQ[d
^ZXVQ
- eb QJRKP[LVQKZMI_Sw, u KPAQJR^ZMwLJ^LKMw/s ns nvvs x71*-xvd
- eb - t QJRKP[LVQKZMI_Sw, u KPAQJR^ZMwLJ^LKMw/s ks nvvs x362*+:xvd
MZKJMQ -d
ZQ[d
> _L wLZSZ]K x^>28>41-:sS12;12sQ:( F1-5s]76<>81s[:2):-x > YMPR [J_Svs
=
_L wLZSZ]K KPAKVRZLK_ROAKEwLJ^LKMwMZXZGOALJ^LKMw[^RLASP^qLJ^LKMw'vs xc^Maqu JK]xvs kvs xR12q ;;s 77nle36e,, KEMxv
21(
YMPR wLZSZ]K 7++/*-6+%/:wx7++/epp+%<71q*,21q2>)%q364p<86r=62p+63:-q/4xvq8:+<41=wv ' YMPR [J_Svv
LZSZ]K MZOS_]Zw>s xsxs xd xv
YMPR wLZSZ]K MKMVRw
GRSNJZMFwxpp'p+:'+wvx
O_LLVQX GRS_XXwGRSZSZRZQKw|'|s = "" x x "" < "" xsxv PM[ZM ^F > [ZL]v MZKJMQVQX ]PQKZQKvs
xsxv
>
YMPR wLZSZ]K < >s =s KPA]W_Mw<s x|r| [[rRPQrFFFF 77nle36e,,xv <
YMPR wLZSZ]K =s ]_LKwwLZSZ]K 21( YMPR =v t < _L KVRZLK_ROv <
YMPR wLZSZ]K >s =s 1n6wKEAPYYLZKw<vv <
YMPR wLZSZ]K ]_LZ SZQXKWw<v
HWZQ f
KWZQ
x_,6>x "" xpx "" xT145>+>x
HWZQ g
KWZQ
x_3:-6<>x "" xpx "" MZOS_]Zw<s x xs xAxv
HWZQ h
KWZQ
xJLx "" xpx "" x]:2+->4x
HWZQ i
KWZQ
QISw[Z]P[ZwLJ^LKMw=s ns ovs xPxs xJK]xvs
xJLx "" xpx "" xR1*2+>62xv
ZQ[
<s
>s
=
YMPR wLZSZ]K >s LJ^LKMw=s os mv =s = <
YMPR wLZSZ]K JOOZMw=v =s < >s VQVK]_Ow=v <
YMPR wLZSZ]K <s >s =
YMPR wLZSZ]K >s
= <s
MZXZGOALJ^LKMw>s
xDBsCtxs
os
=v
=
YMPR >
YJSS PJKZM UPVQ
wLZSZ]K KPAQJR^ZMw]PSJRQAI_SJZv =
YMPR GRSK_^SZw
wLZSZ]K xox
"" x +1 x
"" w wLZSZ]K SZQXKWw
MZOS_]Zw
MZXZGOAMZOS_]Zw
>s
xDBsCxs
x'xvs
x'xs
QJSSvv
YMPR >v
t ov
YMPR [J_Svvv <
PQ = c SZQXKWw>vvvvvvvvvv}',
q'{"%'()*+,-./123456789:;<=>ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_abcdefghiklmnopqrstuvwxy|}',
q'{|yxwvutsrqponmlkihgfedcba_^][ZYXWVUTSRQPONMLKJIHGFEDCBA>=<;:987654321/.-,+*)('%"}'
)
INTO s;
RETURN s;
END;
SELECT s
FROM dual
James' SQL (note: ensure spaces and tabs are preserved or this solution won't work)
SELECT SUBSTR(s,INSTR(s,'<S>')+3,INSTR(s,'</S>')-INSTR(s,'<S>')-3)
FROM (
SELECT DBMS_XMLGEN.getxmltype(LISTAGG(CHR((INSTR(S,b,1,3*LEVEL-2)-DECODE(LEVEL,1,0,INSTR(S,b,1,3*LEVEL-3))-1)*25
+(INSTR(S,b,1,3*LEVEL-1)-INSTR(S,b,1,3*LEVEL-2)-1)*5
+INSTR(S,b,1,3*LEVEL)-INSTR(S,b,1,3*LEVEL-1)-1
+32)) WITHIN GROUP(ORDER BY LEVEL))S
FROM (
SELECT''
||''
||'' S,chr(9) b FROM DUAL
)
CONNECT BY LEVEL<=REGEXP_COUNT(S,b)/3
);