如何从postgresql select查询中获取age()函数的年份

Question

以下查询返回:

SELECT AGE(cast(dob AS date)) 
FROM mas_patient_details;

age
----------
39 years 5 mons 19 days
13 years 2 days
69 years 2 days
41 years 11 mons 25 days

此查询返回:

SELECT age(cast(dob as date)) 
FROM mas_patient_details 
WHERE age <= 59;

age
----------
39 years 5 mons 19 days
13 years 2 days
69 years 2 days
41 years 11 mons 25 

如何从这些查询之一中简单地提取年份？

Answer 1

如果列fu的数据类型为DATE,则可以使用

SELECT EXTRACT(YEAR FROM fu) FROM mydate;

如果是varchar,则使用to_date()将其转换为日期

SELECT EXTRACT(YEAR FROM to_date(fu, <your pattern>)) FROM mydate;

在你的情况下:

select EXTRACT(YEAR FROM age(cast(dob as date))) 
from mas_patient_details 
where age <= 59;