Oracle计算年龄的实用方法总结

--示例1：将字符串转换为日期类型
SELECT TO_DATE('1994-07-01', 'YYYY-MM-DD') FROM DUAL;
--示例2：获取系统当前时间
SELECT SYSDATE FROM DUAL;
--示例3：计算两个日期之间的差值
SELECT MONTHS_BETWEEN(TO_DATE('2022-07-01', 'YYYY-MM-DD'), TO_DATE('1980-05-20', 'YYYY-MM-DD')) FROM DUAL;
--示例4：将日期截取为年份
SELECT TRUNC(MONTHS_BETWEEN(SYSDATE, TO_DATE('1994-07-01', 'YYYY-MM-DD')) / 12) FROM DUAL;

--示例1：计算当前年龄
SELECT TRUNC(MONTHS_BETWEEN(SYSDATE, TO_DATE('1980-05-20', 'YYYY-MM-DD')) / 12) AS AGE FROM DUAL;

--示例1：统计各年龄段人数
SELECT CASE
         WHEN age BETWEEN 18 AND 24 THEN '18-24岁'
         WHEN age BETWEEN 25 AND 30 THEN '25-30岁'
         WHEN age BETWEEN 31 AND 35 THEN '31-35岁'
         ELSE '其他年龄段'
       END AS age_group,
       COUNT(*) AS total
FROM (
       SELECT TRUNC(MONTHS_BETWEEN(SYSDATE, TO_DATE('1990-05-20', 'YYYY-MM-DD')) / 12) AS age
       FROM dual
       UNION ALL
       SELECT TRUNC(MONTHS_BETWEEN(SYSDATE, TO_DATE('1985-05-20', 'YYYY-MM-DD')) / 12) AS age
       FROM dual
       UNION ALL
       SELECT TRUNC(MONTHS_BETWEEN(SYSDATE, TO_DATE('1980-05-20', 'YYYY-MM-DD')) / 12) AS age
       FROM dual
       UNION ALL
       SELECT TRUNC(MONTHS_BETWEEN(SYSDATE, TO_DATE('1975-05-20', 'YYYY-MM-DD')) / 12) AS age
       FROM dual
       UNION ALL
       SELECT TRUNC(MONTHS_BETWEEN(SYSDATE, TO_DATE('1950-05-20', 'YYYY-MM-DD')) / 12) AS age
       FROM dual
)
GROUP BY CASE
           WHEN age BETWEEN 18 AND 24 THEN '18-24岁'
           WHEN age BETWEEN 25 AND 30 THEN '25-30岁'
           WHEN age BETWEEN 31 AND 35 THEN '31-35岁'
           ELSE '其他年龄段'
         END;

SELECT
  FLOOR(MONTHS_BETWEEN(sysdate, date_of_birth) / 12) AS age
FROM
  persons
WHERE
  date_of_birth = 'YYYY-MM-DD';

SELECT
  TRUNC(sysdate - date_of_birth) AS age_in_days
FROM
  persons
WHERE
  date_of_birth = 'YYYY-MM-DD';