Question

HI我的sql中有以下问题来自类似于以下内容的源表：

表1：

Employee    Role    Contract Hours  IS primary Role Valid from
1   Role A  35  Y   01/03/2015
1   Role B  35  Y   01/06/2016
1   Role C  0   N   01/07/2016
2   Role A  20  Y   01/01/2016
2   Role B  0   N   01/01/2016
2   Role C  25  Y   01/04/2016
3   Role A  35  Y   01/04/2016

因此，在员工1的例子中，他于2015年3月1日开始在一家公司工作，于2016年6月1日更改职位，并于2017年7月1日增加了第二个临时职位我需要一个返回任何角色的查询以及最近的主要角色及其合约时间：

Employee    Role    Contract Hours  Valid from  Primary Role – Contract Hours
1   Role A  35  01/03/2015  Role A – 35
1   Role B  35  01/06/2016  Role B – 35
1   Role C  0   01/07/2016  Role B – 35
2   Role A  20  01/01/2016  Role A – 20
2   Role B  0   01/01/2016  Role A – 20 
2   Role C  25  01/04/2016  Role C – 25 
3   Role A  35  01/04/2016  Role A – 35

如果主要角色为N

，我所获得的最佳结果将为附加列返回空值

Select 
“Employee”,
“Role”,
“Contract Hours”,
“Valid From”,
 Case
When “Is primary Role” = Y
Then “Role” + ‘-‘ + “Contract Hours”
    Else NULL
 END as “Primary Role – Contract Hours”

从表1

但是，除了“else Null”之外，我需要找到一种方法，在任何次要角色的有效起始日期之前添加最新的主要值。

Answer 1

/*
DROP TABLE T;
CREATE TABLE T (Employee int,   Role varchar(10),    ContractHours  int,  ISprimaryRole char(1), Validfrom date);
insert into t values
(1,   'Role A',  35 , 'Y' ,  '2015-03-01'),
(1,   'Role B',  35 , 'Y' ,  '2016-06-01'),
(1,   'Role C',  0  , 'N' ,  '2016-07-01'),
(2,   'Role A',  20 , 'Y' ,  '2016-01-01'),
(2,   'Role B',  0  , 'N' ,  '2016-01-01'),
(2,   'Role C' , 25 , 'Y' ,  '2016-04-01'),
(3,   'Role A' , 35 , 'Y' ,  '2016-04-01');
*/


select *
from
(
select *,
        (Select max(t1.validfrom) from t t1 where t1.Employee = t.employee and t1.isprimaryrole = 'Y' and t1.Validfrom <= t.validfrom) maxisp
from    t
) s
left outer join t t1 on t1.employee = s.employee and t1.Validfrom = s.maxisp and t1.isprimaryrole = 'Y'

结果

+----------+--------+---------------+---------------+------------+------------+----------+--------+---------------+---------------+------------+
| Employee | Role   | ContractHours | ISprimaryRole | Validfrom  | maxisp     | Employee | Role   | ContractHours | ISprimaryRole | Validfrom  |
+----------+--------+---------------+---------------+------------+------------+----------+--------+---------------+---------------+------------+
|        1 | Role A |            35 | Y             | 2015-03-01 | 2015-03-01 |        1 | Role A |            35 | Y             | 2015-03-01 |
|        1 | Role B |            35 | Y             | 2016-06-01 | 2016-06-01 |        1 | Role B |            35 | Y             | 2016-06-01 |
|        1 | Role C |             0 | N             | 2016-07-01 | 2016-06-01 |        1 | Role B |            35 | Y             | 2016-06-01 |
|        2 | Role A |            20 | Y             | 2016-01-01 | 2016-01-01 |        2 | Role A |            20 | Y             | 2016-01-01 |
|        2 | Role B |             0 | N             | 2016-01-01 | 2016-01-01 |        2 | Role A |            20 | Y             | 2016-01-01 |
|        2 | Role C |            25 | Y             | 2016-04-01 | 2016-04-01 |        2 | Role C |            25 | Y             | 2016-04-01 |
|        3 | Role A |            35 | Y             | 2016-04-01 | 2016-04-01 |        3 | Role A |            35 | Y             | 2016-04-01 |
+----------+--------+---------------+---------------+------------+------------+----------+--------+---------------+---------------+------------+

如果不满足条件，则替换满足条件的行中的值

1 个答案: