Correlated Subquery for joining summary table original data table

Question

I want to list a set of fields from an inner-query that correspond to calculated fields on an outer-query. A set of date fields on the outer-query signify a range to correlate records on the inner-query. Records on the inner-query have a single date field
which should fall within the outer-query date range. At this point, I cannot determined the correct syntax for this query, but am able to achieve the desired results using a left outer join and case-when arguments on what should be the inner-query records.
Here's my basic SQL right now:
SELECT  DISTINCT a.service,
      a.start_range,   -- start of month
      a.end_range,    -- end of month
      a.availability,
      CASE WHEN YEAR(a.start)=YEAR(o.begin) AND MONTH(a.start)=month(o.begin) THEN o.event_id ELSE NULL END AS 'event_id'
CASE WHEN YEAR(a.start)=YEAR(o.begin) AND MONTH(a.start)=month(o.begin) THEN o.minutes ELSE NULL END AS 'minutes'
FROM   service_availability a LEFT OUTER JOIN 
           service_outage o ON 
a.service=o.service AND
TIMESTAMPDIFF(YEAR,o.begin,NOW())=0
WHERE   TIMESTAMPDIFF(YEAR,a.start,NOW())=0
The limitation with this approach is that the CASE WHEN argument needs to be used for retrieving any fields on the service_outage table. I've tried several approaches including parameters in both the FROM and
WHERE clauses as well as subqueries, but cannot get any to return the data. Is there a better way to achieve this?

Answer 1

Please follow basic Netiquette and post the DDL we need to answer this. Follow industry and ANSI/ISO standards in your datA. You should follow ISO-11179 rules for naming data elements. You should follow ISO-8601 rules for displaying temporal datA. We need
to know the data types, keys and constraints on the table. Avoid dialect in favor of ANSI/ISO Standard SQL.
>> I want to list a set of fields[sic] from an inner-query that correspond to calculated fields [sic] on an outer-query. <<
Columns are not fields. Rows are not records. CASE is an expression, not an argument. Where did you get the terms “inner-query” and “outer-query”? I never heard them before and I have some experience with SQL. We have subqueries; is that what you are trying
say? 
>> A set of date fields [sic] on the outer-query signify a range to correlate records [sic] on the inner-query. Records on the inner-query have a single date field [sic] which should fall within the outer-query date range.<<
You do not know the basic terms or how SQL work. You also posted some weird dialect of an SQL-like language. What is NOW()?? Does that mean CURRENT_TIMESTAMP in your dialect?  Did you know that BEGIN is a reserved word in SQL? 
>> At this point, I cannot determined the correct syntax for this query, but am able to achieve the desired results using a LEFT OUTER JOIN and CASE-when arguments [sic] on what should be the inner-query [sic] records [sic]. Here's my basic SQL right
now: <<
Why are you doing temporal math in SQL? Where is the calendar and report period tables?
Since SQL is a database language, we prefer to do look ups and not calculations. They can be optimized while temporal math messes up optimization. A useful idiom is a report period calendar that everyone uses so there is no way to get disagreements in the DML.
The report period table gives a name to a range of dates that is common to the entire enterprise. 
CREATE TABLE Month_Periods
(month_name CHAR(10) NOT NULL PRIMARY KEY
  CHECK (month_name LIKE '[12][0-9][0-9][0-9]-[01][0-9]-00'),
 month_start_date DATE NOT NULL,
 month_end_date DATE NOT NULL,
 CONSTRAINT date_ordering
  CHECK (month_start_date <= month_end_date),
etc);
These report periods can overlap or have gaps. I like the MySQL convention of using double zeroes for months and years, That is 'yyyy-mm-00' for a month within a year and 'yyyy-00-00' for the whole year. The advantages are that it will sort with the ISO-8601
data format required by Standard SQL and it is language independent. The pattern for validation is '[12][0-9][0-9][0-9]-00-00' and '[12][0-9][0-9][0-9]-[01][0-9]-00'
Why is an outage not an availability status or an event? 
>> The limitation with this approach is that the CASE WHEN argument [sic] needs to be used for retrieving [sic: querying is not retrieving] any fields [sic] on the Service_Outage table<<
We have no DDL! Not even sample data. 
>> I've tried several approaches including parameters in both the FROM and WHERE clauses as well as subqueries, but cannot get any to return the data. <<
Parameters exist in procedure declarations; arguments are the actual values passed in them.  Neither of them as anything to do with a query. 
Want to try again? 
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