select TOP designated employees per department IN A SINGLE qUERY : I HAVE A TABLE AND VALUES 

HOW TO FINED TOP designated employees per department.
TAHNKS  IN ADVANCED  
OUT PUT SHOULD BE
    emp_id	dept_name	emp_name	desig
      1	      IT	    JAFFERY	   DIRECTOR
     12	      QA	     GEORGE  	MANAGER
     13	     ADMIN	     EMILLY	    MANAGER
     15	   DEVELOPMENT	   ABDUL	MANAGER
     16	   DATA	         PATRICK	CLERK

    CREATE TABLE [dbo].[#deptartment]
    (
      [emp_id] [INT] IDENTITY(1, 1) NOT NULL,
      [dept_name] [VARCHAR](100) NULL,
      [emp_name] [VARCHAR](50) NULL ,
      [desig] [VARCHAR](100) NULL
    )
    ON  [PRIMARY]
    GO

    INSERT INTO #deptartment  VALUES ('IT','JAFFERY','DIRECTOR')
    INSERT INTO #deptartment  VALUES ('DEVELOPMENT','CORBIT','PROGRAMMER')
    INSERT INTO #deptartment  VALUES ('DEVELOPMENT','CHANDRA','DBA')
    INSERT INTO #deptartment  VALUES ('IT','KEVIN','MANAGER')
    INSERT INTO #deptartment  VALUES ('IT','ROBERT','SUPERVISOR')
    INSERT INTO #deptartment  VALUES ('QA','NOMAN','ANALYST')
    INSERT INTO #deptartment  VALUES ('ADMIN','CORE','RECEPTIONIST')
    INSERT INTO #deptartment  VALUES ('QA','MADDEN','ANALYST')
    INSERT INTO #deptartment  VALUES ('IT','NORRIS','TECHNICIAN')
    INSERT INTO #deptartment  VALUES ('ADMIN','PATRICK','CLERK')
     INSERT INTO #deptartment  VALUES ('DATA','SONJA','SUPERVISOR')
     INSERT INTO #deptartment  VALUES ('QA','GEORGE','MANAGER')
     INSERT INTO #deptartment  VALUES ('ADMIN','EMILLY','MANAGER')
     INSERT INTO #deptartment  VALUES ('QA','PATRICK','TESTER')
     INSERT INTO #deptartment  VALUES ('DEVELOPMENT','ABDUL','MANAGER')
     INSERT INTO #deptartment  VALUES ('DATA','PATRICK','CLERK')
     INSERT INTO #deptartment  VALUES ('ADMIN','GEORGE','CLERK')
     INSERT INTO #deptartment  VALUES ('DEVELOPMENT','YURIY','SUPERVISOR')
     INSERT INTO #deptartment  VALUES ('DATA','GRAHAM','OPERATOR')