Mysql to Informix query - mysql

Question

I used following query to retrieve information from a mysql table.
SELECT YEARWEEK(fecha,2) ,CONCAT('Semana ', WEEK(fecha)) as y,count(*) as a
FROM mobile09
WHERE fecha BETWEEN TODAY - 30 AND TODAY GROUP BY 1 ORDER BY 1 ASC
How can I get the same result in a Informix database with same tables?

Answer 1

You're going to have to implement your own week of year function for Informix.
Lucky for you, this has already been done at: IBM Developerworks
CREATE FUNCTION day_one_week_one(yyyy INTEGER)
RETURNING DATE
WITH(NOT VARIANT)
DEFINE jan1 DATE;
LET jan1 = MDY(1, 1, yyyy);
RETURN jan1 + MOD(11 - WEEKDAY(jan1), 7) - 3;
END FUNCTION;
CREATE FUNCTION iso8601_weeknum(dateval DATE DEFAULT TODAY)
RETURNING CHAR(2)
WITH(NOT VARIANT)
DEFINE rv CHAR(8);
DEFINE yyyy CHAR(4);
DEFINE ww CHAR(2);
DEFINE d1w1 DATE;
DEFINE tv DATE;
DEFINE wn INTEGER;
DEFINE yn INTEGER;
-- Calculate year and week number.
LET yn = YEAR(dateval);
LET d1w1 = day_one_week_one(yn);
IF dateval < d1w1 THEN
-- Date is in early January and is in last week of prior year
LET yn = yn - 1;
LET d1w1 = day_one_week_one(yn);
ELSE
LET tv = day_one_week_one(yn + 1);
IF dateval >= tv THEN
-- Date is in late December and is in the first week of next year
LET yn = yn + 1;
LET d1w1 = tv;
END IF;
END IF;
LET wn = TRUNC((dateval - d1w1) / 7) + 1;
-- Calculation complete: yn is year number and wn is week number.
-- Format result.
LET yyyy = yn;
IF wn < 10 THEN
LET ww = "0" || wn;
ELSE
LET ww = wn;
END IF
RETURN ww;
END FUNCTION;
Now you should be able to do
select
year(fecha) || iso8601_weeknum(fecha),
'Semana ' || iso8601_weeknum(fecha) as y,
count(*) as a
from
mobile09
where
fecha between today - 30 and today
group by
1, 2
order by
1 asc;