1. 查询天数据

1. 查询当天数据

select * from table1 as n
where n.created_time>=current_date;

2. 查询昨天数据

select * from table1 as n
where n.created_time>=current_date-1 and n.created_time <current_date ;

2. 查询月数据

1. 查询当月数据

select *
from table1 as n
WHERE extract(YEAR FROM created_time) = extract(YEAR FROM now())
and extract(MONTH FROM created_time) = extract(MONTH FROM now()) 

2. 查询上月数据

select *
from table1 as n
where created_time >= date_trunc('month',current_date - interval '1' month)
and created_time < date_trunc('month',current_date)

3. 查询年数据

1. 查询当年数据

select *
from table1 as n
WHERE extract(YEAR FROM created_time) = extract(YEAR FROM now()) ORDER BY created_time

2. 查询去年数据

select *
from table1 as n
where created_time >= date_trunc('year',current_date - interval '1' year)
and created_time < date_trunc('year',current_date)

4.类型转换

1. 查询某天：datetime类型的，需要转换为 date 类型，如果你要查询的字段已经是 date 类型则不需要进行转换
   select t_create
   from table
   where t_create::date = to_date(‘2023-02-08’, ‘YYYY-MM-DD’);
2. string转timestamp类型,按范围查询
   select * from table where create_date >= ‘2023-01-08’::timestamp and create_date < ‘2023-02-08’::timestamp;
3. 时间戳Long转Timestamp
   select TO_TIMESTAMP(1512490630)
4. string转data,只能得到年月日，得不到时分秒
   select to_date(‘2023-01-28 12:55:05’)
5. 当前日期 select current_date
6. 带时区的时分秒值 select current_time;也可以使用current_time(precision)，将结果在四分之一秒的范围内四舍五入到位数，比如select current_time(2)；对应没有时区的值：select localtime;
7. 带时区的年月日时分秒值 select current_timestamp; 对应没有时区的值：select localtimestamp;