DATE_TRUNC
DATE_TRUNC('unit', timestamp)
- 命令说明:根据指定的日期部分(如小时、周或月)截断时间戳表达式或文本。
- 参数说明:unit可以是SECOND、MINUTE、HOUR、DAY、WEEK、MONTH、QUARTER或者YEAR。
- SECOND:返回秒数对应的时间
- MINUTE:返回分钟数对应的时间
- HOUR:返回当天整点时刻
- DAY:返回当天零点
- WEEK:返回周一零点
- MONTH:返回当月第一天零点
- QUARTER:返回本季度第一天零点
- YEAR:返回本年度第一天零点
- 示例:
select date_trunc('second', now()); +--------------------+ | _col0 | +--------------------+ | 2018-12-27 14:08:53| +--------------------+ select date_trunc('minute', now()); +--------------------+ | _col0 | +--------------------+ | 2018-12-27 14:15:00| +--------------------+ select date_trunc('hour', now()); +--------------------+ | _col0 | +--------------------+ | 2018-12-27 14:00:00| +--------------------+ select date_trunc('day', now()); +--------------------+ | _col0 | +--------------------+ | 2018-12-27 00:00:00| +--------------------+ select date_trunc('week', now()); +--------------------+ | _col0 | +--------------------+ | 2018-12-24 00:00:00| +--------------------+ select date_trunc('month', now()); +--------------------+ | _col0 | +--------------------+ | 2018-12-01 00:00:00| +--------------------+ select date_trunc('quarter', now()); +--------------------+ | _col0 | +--------------------+ | 2018-10-01 00:00:00| +--------------------+ select date_trunc('year', now()); +--------------------+ | _col0 | +--------------------+ | 2018-01-01 00:00:00|