Pertama, tulis ulang kueri Anda. Gunakan tampilan atau ekspresi tabel umum untuk menghindari pengulangan diri Anda tiga kali untuk SELECT
. Anda , GROUP BY
, ORDER BY
klausa. Kueri Anda menjadi:
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
Kemudian, untuk memastikan bahwa salah satu grup yang Anda inginkan akan tersedia di hasil, Anda memiliki banyak opsi.
Anda dapat menggunakan 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
Solusi yang sama sekali berbeda akan melibatkan 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
Pada contoh kedua, Anda juga dapat melakukannya tanpa CTE dan menggunakan SELECT bersarang untuk groups
meja. Sangat mudah untuk melihat bagaimana contoh kedua lebih mudah untuk dikembangkan di masa depan, jika persyaratan Anda berubah.