oracle - 从 PLSQL 中的表派生函数

Question

我创建了一个演示函数来在 PLSQL 中添加两个数字:

create or replace FUNCTION Addition(    
    x number,
    y number
    )     
    RETURN number
AS
    result number; 
BEGIN
    result := x+y;  
    RETURN result;  
END; 
/
commit;

现在，我有下表:

Seq  Inputl  lnput2  Function
---  ------  ------  ----------------
A         1       2  Addition
B         3       4  Subtraction
C         5       6  Addition
D         7       8  Addition
E         9      10  Addition

我必须在我的程序中使用函数，如下所述:

select * bulk collect into data from table order by Seq asc;

for i in 1 .. data.count loop
   result(i) := data(i).function(data(i).Input1,data(i).Input2);
end loop;

我使用这种方式时遇到错误。

还有其他方法可以实现吗？

Answer 1

您可以创建一个函数，它接受来自您的表的操作名称，例如“加法”或“减法”:

create or replace function do_the_arith
    ( operation varchar2
    , x number
    , y number )
    return number
as
begin
    return
        case upper(operation)
            when 'ADDITION' then x + y
            when 'MULTIPLICATION' then x * y
            when 'SUBTRACTION' then x - y
            when 'DIVISION' then x / nullif(y,0)  -- to avoid zero divide
            when 'POWER' then power(y,y)
            when 'LOG' then log(x,y)
        end;
end do_the_arith;
/

with t (seq, input1, input2, operation) as
     ( select 'A', 1,  2, 'Addition' from dual union all
       select 'B', 3,  4, 'Multiplication' from dual union all
       select 'C', 5,  6, 'Subtraction' from dual union all
       select 'D', 7,  8, 'Power' from dual union all
       select 'E', 9, 10, 'Log' from dual )
select t.*
     , do_the_arith(operation, input1, input2) as result
from   t;

SEQ     INPUT1     INPUT2 OPERATION          RESULT
--- ---------- ---------- -------------- ----------
A            1          2 Addition                3
B            3          4 Multiplication         12
C            5          6 Subtraction            -1
D            7          8 Power            16777216
E            9         10 Log            1.04795163