Case when help

Question

Please advise how can i use the following logic to create a case-when and incluse all the desired results in one select from table t1.
IF upper(prd) in ('AB','AC','AE')
then
     If acc2 >= 0 then
  Cur1 :=ccy2
  Cur2 :=ccy1
  amt:=acc2
    elsif
  acc2 < 0 then
  Cur1 :=ccy1
  Cur2 :=ccy2
          IF acc1 IS NOT NULL then
          amt := acc1
          else
          amt := -1 * r1 * acc2
          End if;
    End if;
elsif
upper(prd) IN ('AZ') then
    If acc2 >= 0 then
    Cur1 :=ccy2;
    Cur2:=ccy1;
     amt := r4;
    elsif acc2 < 0 then
    Cur1 =ccy1
     Cur2=ccy2
        if r3 IS NOT NULL THEN
        amt := r3
        else
        amt=-1 * r2 * r4;
        End If;
    END If;
End if;

Answer 1

Hi,
Here's another way:
SELECT     CASE
             WHEN  UPPER (prd) NOT IN ('AB', 'AC', 'AE', 'AZ')
                                      THEN  NULL
          WHEN  acc2 >= 0          THEN  ccy2
          WHEN  acc2 <  0          THEN  ccy1
     END     AS cur1
,     CASE
             WHEN  UPPER (prd) NOT IN ('AB', 'AC', 'AE', 'AZ')
                                      THEN  NULL
          WHEN  acc2 >= 0          THEN  ccy1
          WHEN  acc2 <  0          THEN  ccy2
     END     AS cur2
,     CASE
          WHEN  UPPER (prd) IN ('AB', 'AC', 'AE')
          THEN  CASE
                   WHEN  acc2 >= 0          THEN  acc2
                   WHEN  acc2 <  0          THEN  NVL ( acc1
                                                            , -r1 * acc2
                END
          WHEN  UPPER (prd) IN ('AZ')
          THEN  CASE
                     WHEN  acc2 >= 0          THEN  r4
                     WHEN  acc2 <  0          THEN  NVL ( r3
                                                            , -r2 * r4
                END
     END     AS amt
...Note that the expression for amt shows how to use nested CASE statements. That can be very useful in CASE statements where the conditions are very complicated. However, I do not think that is situation here: I find Ben's suggestion (WHEN x AND y THEN ... WHEN x AND NOT y THEN ...) clearer for computing amt.