postgresql实现获取一个月的数据,若哪天不存在数据,填充0
表格原始数据
查询10-01到10-30之间订单数据
sql1:
SELECT
to_char( date_trunc( ‘day’, t2.rtime ), ‘yyyy-MM-DD’ ) AS TIME,
SUM (t2.money ) AS “totalMoney”
FROM
aoo t2
WHERE
t2.rtime <= to_date( ‘2018-10-30’, ‘YYYY-MM-DD’ )
AND t2.rtime >= to_date( ‘2018-10-01’, ‘YYYY-MM-DD’ )
GROUP BY
TIME
结果为:
其中有些天没有数据,要实现成如下效果:
首先生成一个连续日期的函数用于拼接generate_series ( to_timestamp ( ‘2018-10-01’, ‘YYYY-MM-DD hh24:mi:ss’ ), to_timestamp ( ‘2018-10-31’, ‘YYYY-MM-DD hh24:mi:ss’ ), ‘1 days’ )
sql2:
SELECT
to_char ( b, ‘YYYY-MM-DD’ ) AS time
FROM
generate_series