INFORMIX: a count of each elementname from sub-query of distinct callid and the Max varable value - informix

Question

Here are my tables:
I need to get a count of the elementname for each each callid where the varname equals 'eCounter' and the varvalue is the greatest.
The tables are relational by elementid one (element) to many (elementdetail). I include the format of the actual elementid so you don't assume they are consecutive numbers.
I tried the following code just to get the Max varvalue/elementid for each call, but that did not work out either.
SELECT MAX(a.varvalue) as MAXvarvalue, b.callgui
FROM elementdetail AS a, element AS b
WHERE (a.elementid = b.elementid) AND (a.varname = 'eCounter')
GROUP BY varname, callguid
This is what I need the results to look like.

Answer 1

Using the latest Informix version ( 14.10.XC1 ).
Assuming the following tables:
CREATE TABLE element
(
callid INTEGER,
elementid BIGINT,
elementname CHAR( 20 )
);
CREATE TABLE elementdetail
(
elementid BIGINT,
varname CHAR( 20 ),
varvalue INTEGER
);
Which are populated with your sample data ( OCR to the rescue, you really should post your sample data and tables as text, not images ):
INSERT INTO element VALUES ( 1, 1001901560322810000, 'set_Page1' );
INSERT INTO element VALUES ( 1, 1001921560322810000, 'set_Page5' );
INSERT INTO element VALUES ( 1, 1001181560322820000, 'set_Page4' );
INSERT INTO element VALUES ( 1, 1001021560322820000, 'set_Page3' );
INSERT INTO element VALUES ( 1, 1001331560322830000, 'set_Page6' );
INSERT INTO element VALUES ( 2, 1002281560322920000, 'set_Page1' );
INSERT INTO element VALUES ( 2, 1002301560322920000, 'set_Page5' );
INSERT INTO element VALUES ( 2, 1002881560322940000, 'set_Page4' );
INSERT INTO element VALUES ( 3, 1002271560322950000, 'set_Page1' );
INSERT INTO element VALUES ( 3, 1002951560322970000, 'set_Page4' );
INSERT INTO element VALUES ( 3, 1002231560322980000, 'set_Page6' );
INSERT INTO element VALUES ( 4, 1002781560323000000, 'set_Page1' );
INSERT INTO element VALUES ( 4, 1002891560323020000, 'set_Page5' );
INSERT INTO element VALUES ( 4, 1002391560323040000, 'set_Page4' );
INSERT INTO elementdetail VALUES ( 1001901560322810000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1001901560322810000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001921560322810000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1001921560322810000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001181560322820000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1001181560322820000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001021560322820000, 'eCounter', 4 );
INSERT INTO elementdetail VALUES ( 1001021560322820000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1001331560322830000, 'eCounter', 5 );
INSERT INTO elementdetail VALUES ( 1001331560322830000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002281560322920000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1002281560322920000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002301560322920000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1002301560322920000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002881560322940000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1002881560322940000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002271560322950000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1002271560322950000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002951560322970000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1002951560322970000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002231560322980000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1002231560322980000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002781560323000000, 'eCounter', 0 );
INSERT INTO elementdetail VALUES ( 1002781560323000000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002891560323020000, 'eCounter', 1 );
INSERT INTO elementdetail VALUES ( 1002891560323020000, 'other_variables', NULL );
INSERT INTO elementdetail VALUES ( 1002391560323040000, 'eCounter', 2 );
INSERT INTO elementdetail VALUES ( 1002391560323040000, 'other_variables', NULL );
We can do something like this, making use of a CTE:
WITH cte_element AS
(
SELECT
e.callid,
e.elementname,
d.varvalue
FROM
element AS e
INNER JOIN
elementdetail AS d
ON
e.elementid = d.elementid
WHERE
d.varname = 'eCounter'
ORDER BY
e.callid,
d.varvalue
)
SELECT
vt1.elementname,
COUNT( vt1.elementname ) AS count_elementname
FROM
(
SELECT
tmp1.callid,
tmp1.elementname,
tmp1.varvalue
FROM
cte_element AS tmp1
WHERE
tmp1.varvalue =
(
SELECT
MAX( tmp2.varvalue )
FROM
cte_element AS tmp2
WHERE
tmp1.callid = tmp2.callid
GROUP BY
tmp2.callid
)
) AS vt1
GROUP BY
vt1.elementname
;
-- Results
elementname count_elementname
set_Page6 2
set_Page4 2
Still using a a recent version of Informix, using windowing instead of a CTE:
SELECT
vt1.elementname,
COUNT( vt1.elementname ) AS count_elementname
FROM
(
SELECT
e.callid,
e.elementname,
d.varvalue,
RANK() OVER
(
PARTITION BY e.callid ORDER BY e.callid, d.varvalue DESC
) AS rank
FROM
element AS e
INNER JOIN
elementdetail AS d
ON
e.elementid = d.elementid
WHERE
d.varname = 'eCounter'
ORDER BY
e.callid,
d.varvalue
) AS vt1
WHERE
vt1.rank = 1
GROUP BY
vt1.elementname
;
-- Results
elementname count_elementname
set_Page6 2
set_Page4 2
With an older Informix version, without CTE's or windowing, so we use a temporary table:
SELECT
e.callid,
e.elementname,
d.varvalue
FROM
element AS e
INNER JOIN
elementdetail AS d
ON
e.elementid = d.elementid
WHERE
d.varname = 'eCounter'
ORDER BY
e.callid,
d.varvalue
INTO TEMP temp_element
;
SELECT
vt1.elementname,
COUNT( vt1.elementname ) AS count_elementname
FROM
(
SELECT
tmp1.callid,
tmp1.elementname,
tmp1.varvalue
FROM
temp_element AS tmp1
WHERE
tmp1.varvalue =
(
SELECT
MAX( tmp2.varvalue )
FROM
temp_element AS tmp2
WHERE
tmp1.callid = tmp2.callid
GROUP BY
tmp2.callid
)
) AS vt1
GROUP BY
vt1.elementname
;
-- Results
elementname count_elementname
set_Page6 2
set_Page4 2
I have no idea of how any of this queries will scale when you use a more robust data set ( hundred thousands or millions of rows on each table ).
I have not tested any corner case, for example, when a callid has 2 elementname with the same eCounter varvalue values.