Problem using DECODE() function with a Query of Queries

Question

I
posted
on my blog about an issue I was having trying to use the PL/SQL
DECODE() function with a Coldfusion Query of Queries. This function
works fine when you query a database for information. However, when
you query another query, it seems that CF doesn't recognize it. I
got errors stating that it found a left parenthesis where it
expected a FROM key word. Here is a simplified version of what I am
trying to do:
quote:
<!--- Simulated query; similar to what I was calling from
my database --->
<cfscript>
qOriginal = queryNew("Name,Email,CountryCode",
"VarChar,VarChar,VarChar");
newRow = queryAddRow(qOriginal, 5);
querySetCell(qOriginal, "Name", "Joe", 1);
querySetCell(qOriginal, "Email", "[email protected]", 1);
querySetCell(qOriginal, "CountryCode", "AMER", 1);
querySetCell(qOriginal, "Name", "Sally", 2);
querySetCell(qOriginal, "Email", "[email protected]", 2);
querySetCell(qOriginal, "CountryCode", "AMER", 2);
querySetCell(qOriginal, "Name", "Bob", 3);
querySetCell(qOriginal, "Email", "[email protected]", 3);
querySetCell(qOriginal, "CountryCode", "ASIA", 3);
querySetCell(qOriginal, "Name", "Mary", 4);
querySetCell(qOriginal, "Email", "[email protected]", 4);
querySetCell(qOriginal, "CountryCode", "EURO", 4);
querySetCell(qOriginal, "Name", "John", 5);
querySetCell(qOriginal, "Email", "[email protected]", 5);
querySetCell(qOriginal, "CountryCode", "EURO", 5);
</cfscript>
<cfquery name="qCountries" dbtype="query">
SELECT DISTINCT(CountryCode) AS CountryCode,
DECODE(states, "AMER", "North America &amp; Canada",
"EURO", "Europe &amp; Africa", "ASIA", "Japan &amp;
Asia","") CountryName
FROM qOriginal
ORDER BY CountryCode
</cfquery>
<cfdump var="#qCountries#">
<!--- ========== END OF CODE ========== --->
So running this returned the following error:
Query Of Queries syntax error.
Encountered "(. Incorrect Select Statement, Expecting a
'FROM', but encountered '(' instead, A select statement should have
a 'FROM' construct.
Does anybody know why this doesn't work? Is it just not
supported? Please note that I have also tried to use the CASE()
function instead of DECODE() and that resulted in basically the
same error. For now I an looping over my distinct query with a
switch statement and manually loading a new query with the data how
I want it. But it would be a lot cleaner and less code to have the
DECODE() to work. Thx!

Answer 1

DECODE() is an Oracle function, not generic SQL. Q-of-Q is a
very limited subset of SQL and lacks many functions and clauses
available in standard SQL, especially what you may be used to using
in your particular RDBMS.
See
Query
of Queries user guide
Phil