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我使用PostgreSQL 9.5 和我有一个表是这样的:最近的日期时间对PostgreSQL 9.5
CREATE TABLE tracks (
track bigserial NOT NULL,
time_track timestamp,
CONSTRAINT pk_aircraft_tracks PRIMARY KEY (track)
);
我想获得轨道由SELECT操作日期时间的最接近的值。 e.g,如果我有:
track datatime
1 | 2016-12-01 21:02:47
2 | 2016-11-01 21:02:47
3 |2016-12-01 22:02:47
对于输入DATATIME 2016年12月1日21点00分,轨道是2
我foud出去整数Is there a postgres CLOSEST operator?类似queston。 但它不与DATATIME工作或PostgreSQL 9.5:
SELECT * FROM
(
(SELECT time_track, track FROM tracks WHERE time_track >= now() ORDER BY time_track LIMIT 1) AS above
UNION ALL
(SELECT time_track, track FROM tracks WHERE time_track < now() ORDER BY time_track DESC LIMIT 1) AS below
)
ORDER BY abs(?-time_track) LIMIT 1;
错误:
ERROR: syntax error at or near "UNION"
LINE 4: UNION ALL
'AS above'和'AS以下“是多余的。 – Abelisto