Nejprve svůj dotaz přepište. Použijte pohledy nebo běžný tabulkový výraz, abyste se u SELECT
neopakovali třikrát , GROUP BY
, ORDER BY
doložky. Váš dotaz se změní na:
WITH data AS (
SELECT(CASE WHEN time_dtm > SYSDATE -1 THEN '0-1 day'
WHEN time_dtm > SYSDATE -2 AND
time_dtm < SYSDATE -1 THEN '1-2 days'
WHEN time_dtm > SYSDATE -3 AND
time_dtm < SYSDATE -2 THEN '2-3 days'
WHEN time_dtm > SYSDATE -4 AND
time_dtm < SYSDATE -3 THEN '3-4 days'
WHEN time_dtm > SYSDATE -5 AND
time_dtm < SYSDATE -4 THEN 'Closed'
END) AS Age
FROM table_1
WHERE id IN (1,2,3)
)
SELECT Age, COUNT(*)
FROM data
GROUP BY Age
ORDER BY Age
Abyste si byli jisti, že ve výsledku bude k dispozici jakákoli z vámi požadovaných skupin, máte spoustu možností.
Mohli byste použít UNION ALL
:
WITH data AS (
SELECT(CASE WHEN time_dtm > SYSDATE -1 THEN '0-1 day'
WHEN time_dtm > SYSDATE -2 AND
time_dtm < SYSDATE -1 THEN '1-2 days'
WHEN time_dtm > SYSDATE -3 AND
time_dtm < SYSDATE -2 THEN '2-3 days'
WHEN time_dtm > SYSDATE -4 AND
time_dtm < SYSDATE -3 THEN '3-4 days'
WHEN time_dtm > SYSDATE -5 AND
time_dtm < SYSDATE -4 THEN 'Closed'
END) AS Age
FROM table_1
WHERE id IN (1,2,3)
-- The below will add one record for every desired Age group
UNION ALL
SELECT '0-1 day' FROM DUAL UNION ALL
SELECT '1-2 days' FROM DUAL UNION ALL
SELECT '2-3 days' FROM DUAL UNION ALL
SELECT '3-4 days' FROM DUAL UNION ALL
SELECT 'Closed' FROM DUAL
)
SELECT Age, COUNT(*) - 1 -- Subtract the extra record again
FROM data
GROUP BY Age
ORDER BY Age
Zcela odlišné řešení by zahrnovalo LEFT OUTER JOINs
:
-- Groups is a dynamic table that contains the date ranges and their "Age" label
WITH groups AS (
SELECT SYSDATE -1 lower, SYSDATE upper, '0-1 day' Age FROM DUAL UNION ALL
SELECT SYSDATE -2 , SYSDATE -1 , '1-2 days' FROM DUAL UNION ALL
SELECT SYSDATE -3 , SYSDATE -2 , '2-3 days' FROM DUAL UNION ALL
SELECT SYSDATE -4 , SYSDATE -3 , '3-4 days' FROM DUAL UNION ALL
SELECT SYSDATE -5 , SYSDATE -4 , 'Closed' FROM DUAL
)
SELECT g.Age, NVL(SUM(t.counter), 0)
FROM groups g
-- LEFT OUTER JOINing "table_1" to "groups" will ensure that every group
-- appears at least once in the result
LEFT OUTER JOIN (
SELECT 1 counter, t.* FROM table_1 t WHERE t.id IN (1,2,3)
) t
ON t.time_dtm >= g.lower
AND t.time_dtm < g.upper
GROUP BY g.Age
ORDER BY g.Age
Ve druhém příkladu byste se také mohli obejít bez CTE a použít vnořený SELECT pro groups
stůl. Je snadné vidět, jak je v budoucnu jednodušší vyvinout druhý příklad, pokud by se vaše požadavky změnily.