Question

I am trying to work this solution on how to collapse the records based on a value..

Table 1(Input)

 Emp_ID Start_Date  End_Date    Rating  Department  Salary
2000    01012011    12312011    A   HR          10000
2000    01012012    12319999    A   HR          20000
3000    01012011    12312011    B   Operations  50000
3000    01012012    12312012    B   Operations  60000
3000    01012013    12319999    C   Operations  70000

Table 2(Output)

 Emp_ID Start_Date  End_Date    Rating  Department
2000    01012011    12319999    A   HR
3000    01012011    12312012    B   Operations
3000    01012013    12319999    C   Operations

Database is oracle. I just need some start on how to solve this problem so that i can work on it..

Thanks in Advance..

EDIT: Assuming that Table 1 & Table 2 has EMP_NAME column. But i am not able to load this column in table2 as group by wont let me do that..(I am talking abt the soln given by Pablo Santa Cruz)

Any solutions on this..

EDIT: Edited the table structure agan..sorry for confusion

Answer 1

Try this:

select emp_id, rating, min(start_date), max(end_date)
  from table_1
 group by emp_id, rating

If you need to actually store the values on table_2 table, start the previous SQL statement with create table table_2 as.

Considering what you’ve comment, you can do:

create table table_2 as
select emp_id, rating, min(start_date), max(end_date), 
       'EMP_DEPT_INFO' as emp_deparment
  from table_1
 group by emp_id, rating

Other possibility might be creating the table first, and then doing an alter table to include the new column.