在同一个表中的多个列上分组

Question

表员工：

╔═══════════════════════════════════════════════════╗
║ emp_id  emp_position  emp_start_date employer_id  ║
╠═══════════════════════════════════════════════════╣
║ 1234    Associate       08/08/08        7657      ║
║ 1234    Associate       01/01/11        3345      ║
║ 1234    Manager         04/03/13        9483      ║
║ 1234    Manager         04/05/15        2345      ║
╚═══════════════════════════════════════════════════╝

如何构造查询以获取每个emp_role的最早日期，并且查询应仅返回持有多个帖子的员工。

选择smp.emp_id，smp.emp_position，smp.cnt（通过emp_id，emp_position选择emp_id，emp_position，count（*）作为来自员工组的cnt）smp其中smp.cnt＆gt; 1

Answer 1

select 
  emp_position,
  min(emp_start_date)
from
  Employee
group by
  emp_position

Answer 2

尝试此查询

SELECT emp_position, MIN(emp_start_date)
FROM Employee
GROUP BY emp_position