如何根据sql中的月份字段比较两个日期

Question

如何根据 sql 中的月份字段比较两个日期？

有人可以举一个例子来显示在经理加入的那几个月里加入的员工姓名吗？

我试过这些：

SELECT e_name
FROM emp5 e,
    department1 d,
    manager m
WHERE e.e_id = d.empno
    AND m.deptno = d.deptno
    AND month(e.hiredate) = month(m.hiredate);

SELECT e_name
FROM emp5 e,
    department1 d,
    manager m
WHERE e.e_id = d.empno
    AND m.dep tno = d.deptno
    AND month(e.hiredate) = month(m.hiredate)

SELECT e_name
FROM emp5 e,
    department1 d,
    manager m
WHERE e.e_id = d.empno
    AND m.deptno = d.deptno
    AND dd - mon - yy(e.hiredate, '%m-%y') = dd - mon - yy(m.hiredate, '%m-%y');



SELECT e_name
FROM emp5 e,
    department1 d,
    manager m
WHERE e.eid = d.empno
    AND m.deptno = d.deptno
    AND extract(month FROM e.hiredate) = extract(month FROM m.hiredate);

这是我的 emp5 表 –

E_ID     E_NAME                   SALARY     HIREDATE 
----- ------------------------- ---------- --------- 
e01   Komal Pandya              13000       02-FEB-15 
e02   Ganesh Patel              20000       01-FEB-15 

Answer 1

假设您的日期存储为DATE 列，这是从日期中提取月份和年份的两种简单方法：

SQL> select extract(month from sysdate), extract(year from sysdate) from dual;

EXTRACT(MONTHFROMSYSDATE) EXTRACT(YEARFROMSYSDATE)
------------------------- ------------------------
                        3                     2016

SQL> select to_char(sysdate, 'mm/yyyy') from dual;

TO_CHAR
-------
03/2016