我有一个包含子查询的 Postgres 查询,并且只输出 12 行数据,这正是我希望它看起来的样子。这些行中的每一行代表数据库中所有年份的数据的月平均值,每个月一行。查询:
SELECT
to_char(to_timestamp(to_char(subquery2.month, '999'), 'MM'), 'Mon') AS Month,
subquery2.month AS Month_num,
round(AVG(subquery2.all_use_tot), 2) AS Average_Withdrawals,
round(AVG(subquery2.all_cu_tot), 2) AS Average_Consumptive_Use
FROM
(SELECT
subquery1.month,
subquery1.year,
sum(subquery1.liv_tot) AS all_use_tot,
sum(subquery1.CU_total) AS all_cu_tot
FROM
(SELECT
EXTRACT('Month' FROM withdrawals.begintime) AS month,
EXTRACT(YEAR FROM withdrawals.begintime)::int AS year,
tdx_ic_use_type.use_type_code AS Use_type,
sum(withdrawals.withdrawalvalue_mgd) AS liv_tot,
(tdx_ic_use_type.cufactor)*(sum(withdrawals.withdrawalvalue_mgd)) AS CU_total
FROM
medford.tdx_ic_use_type,
medford.withdrawalsites
JOIN medford.subshed2 ON ST_Contains(medford.subshed2.the_geom, medford.withdrawalsites.the_geom)
JOIN medford.withdrawals ON medford.withdrawals.ic_site_id = medford.withdrawalsites.ic_site_id
WHERE
subshed2.id = '${param.shed_id}' AND
withdrawalsites.ic_pr_use_type_id = tdx_ic_use_type.use_type_code AND
withdrawals.intervalcodes_id = 2
GROUP BY
year,
extract('Month' from withdrawals.begintime),
tdx_ic_use_type.cufactor,
Use_type
ORDER BY
year, extract('Month' from withdrawals.begintime) ASC
) AS subquery1
GROUP BY
subquery1.year,
subquery1.month
) AS subquery2
GROUP BY
subquery2.month
ORDER BY
subquery2.month
输出的样子:
"Jan" 1 1426.50 472.65
"Feb" 2 1449.00 482.10
"Mar" 3 1459.50 485.55
"Apr" 4 1470.00 489.00
"May" 5 1480.50 492.45
"Jun" 6 1491.00 495.90
"Jul" 7 1489.50 493.35
"Aug" 8 1512.00 502.80
"Sep" 9 1510.50 500.25
"Oct" 10 1533.00 509.70
"Nov" 11 1543.50 513.15
"Dec" 12 1542.00 510.60
我从数据库中的日期时间列中提取的月份列。我正在使用此查询的结果并将其存储在一个数组中,但我想为表中存在的每一年重复一次这些确切的结果。因此,如果数据库中有 2 年的数据,则应该有 24 个输出行,或者,12 个相同的行重复两次。如果数据库中有 3 年的数据,则应该有 36 行输出,或者 12 行相同的行重复 3 次。如何在查询中完成此操作?有没有办法根据列中的值循环查询(即日期时间字段中存在的年数?)