oracle sql 高级

1  时间

 

如果是从当前时间到前一个月的这个时候之间的记录总条数：

 

select count(1)

  from uis_md_stcustom u

 where firsttime between add_months(sysdate,-1) and sysdate; 

 

 

如果是求当前时间的前面一个月的内的记录总条数：

 

select count(1)

  from uis_md_stcustom u

 where to_char(firsttime,'mm') = to_char(add_months(sysdate,-1),'mm');

 

 

2 IN/ANY

 

IN- Equal toany member in the list
ANY- Compare value to**each** value returned by the subquery
ALL- Compare value to**EVERY** value returned by the subquery

<ANY()- less than maximum
>ANY()- more than minimum
=ANY()- equivalent toIN>ALL()- more than the maximum
<ALL()- less than the minimum

eg:

Find the employees who earn the same salary as the minimum salary for each department-

SELECT last_name, salary,department_id
FROM employees
WHERE salary IN(SELECT MIN(salary)FROM employees
                 GROUPBY department_id);

Employees who are not IT Programmers and whose salary is less than that of any IT programmer-

SELECT employee_id, last_name, salary, job_id
FROM employees
WHERE salary <ANY(SELECT salary
                 FROM employees
                 WHERE job_id ='IT_PROG')AND job_id <>'IT_PROG';

Employees whose salary is less than the salary ofall employees with a job ID of IT_PROG and whose job is not IT_PROG-

SELECT employee_id,last_name, salary,job_id
FROM employees
WHERE salary <ALL(SELECT salary
                 FROM employees
                 WHERE job_id ='IT_PROG')AND job_id <>'IT_PROG;