Conditional order by clause with multiple columns

Question

I would like to know whether it is possible to include multiple columns in a conditional order by clause.
Ex: I have written the following PL / SQL :
CREATE PROCEDURE GetProducts
@OrderBy VARCHAR(50),
@Input2 VARCHAR(30)
AS
BEGIN
SET NOCOUNT ON
SELECT Id, ProductName, Description, Price, Quantity
FROM Products
WHERE ProductName LIKE @Input2
ORDER BY
CASE               
WHEN @OrderBy = 'ProductNameAsc' THEN ProductName
END ASC,
CASE
WHEN @OrderBy = 'ProductNameDesc' THEN ProductName
END DESC
END
Now I want to include when the Orderby - "Productnameasc" then order by productname, price, stdate
else
orderby productname, crdate, category
Could this be done? I tried it, but couldn't get this to work.
Any help is greatly appreciated.

Answer 1

Since matching ORDER BY columns have different data types (first column for CLERK is sal - number, first column for MANAGER deptno is number but first column for "else" is a string) we need to convert number to string but preserve number sort order. Since DEPTNO is NUMBER(2) we will use TO_CHAR with format 'S00'. Since SAL is NUMBER(7,2) we will use TO_CHAR with format model 'S00000D00'. For EMPNO we will use TO_CHAR with format model 'S0000'.
select  deptno,
        empno,
        ename,
        job,
        sal
  from  emp
  order by case job
             when 'CLERK' then to_char(sal,'S00000D00')
             when 'MANAGER' then to_char(deptno,'S00')
             else ename
           end,
           case job
             when 'CLERK' then to_char(deptno,'S00')
             else job
           end,
           case job
             when 'CLERK' then job
             when 'MANAGER' then to_char(empno,'S0000')
           end
    DEPTNO      EMPNO ENAME      JOB              SAL
        20       7369 SMITH      CLERK            800
        30       7900 JAMES      CLERK            950
        20       7876 ADAMS      CLERK           1100
        10       7934 MILLER     CLERK           1300
        10       7782 CLARK      MANAGER         2450
        20       7566 JONES      MANAGER         2975
        30       7698 BLAKE      MANAGER         2850
        30       7499 ALLEN      SALESMAN        1600
        20       7902 FORD       ANALYST         3000
        10       7839 KING       PRESIDENT       5000
        30       7654 MARTIN     SALESMAN        1250
    DEPTNO      EMPNO ENAME      JOB              SAL
        20       7788 SCOTT      ANALYST         3000
        30       7844 TURNER     SALESMAN        1500
        30       7521 WARD       SALESMAN        1250
14 rows selected.
SQL>  SY.