oracle sql query to display one row for each deptid

Guys i want to write an oracle sql query for table A of the following records

--------------------------
 R_ID    D_ID       DEPT     
--------------------------- 
  1      200        CLERK
   1        50       CLERK
   2       190      MANAGER
   2    开发者_高级运维   134       DPTY MANAGER
   3       12        SERVICE MANAGER

and the result should be like below , ie the first row in all the R_ID

--------------------------
 R_ID    D_ID       DEPT     
--------------------------- 
  1       200      CLERK
  2       190      MANAGER
  3       12       SERVICE MANAGER

kindly help me.

---

As Ronnis mentioned, I'm not sure how you are ordering the rows, but this is how you would do it in general. Note just substitute the correct ordering in the ORDER BY clauses.

SELECT DISTINCT R_ID
    , first_value(D_ID) over (partition by R_ID order by D_ID) D_ID
    , first_value(DEPT) over (partition by R_ID order by D_ID) DEPT
FROM your_table
ORDER BY R_ID;

Hope this helps!

---

SELECT R_ID, D_ID, DEPT
FROM
(
 SELECT R_ID, D_ID, DEPT, ROW_NUMBER() over(partition by R_ID order by D_ID) r
) WHERE R=1 

---

SELECT min(r_id), min(d_id), dept
FROM the_table_with_no_name
GROUP BY dept;