動態PL/SQL查詢，如何忽略空參數？

Question

我有一個有多個參數的PL/SQL過程。當一個Web應用程序調用的程序，如果它不使用特定的參數，它傳遞的是空，即

procedure test (param1 in varchar2, param2 in varchar2, param3 in varchar2, cursor out sys_refcursor) 
... 
end procedure test; 

我想打一個SQL查詢，其中包括我在給定的參數WHERE子句僅在參數不爲null。有沒有辦法在一個優雅的方式來實現這一目標，比建設中的SQL查詢字符串，然後打開遊標爲字符串，這樣

vSQL := 'SELECT * from TABLE WHERE something = something_else'; 
if param1 IS NOT NULL 
    vSQL := vSQL || 'AND some_param = ' || param1; 

Answer 1

其他我已經回答了類似的問題on dba.stackexchange.com

Answer 2

你可以把它的所有代碼到一個單一的選擇

SELECT * from TABLE WHERE something = something_else 
AND ((param1 IS NOT NULL AND some_param = param1) OR 1) 

Answer 3

創建一個測試表：

create table testtab 
(
name_first varchar2(50), 
name_last varchar2(50), 
name_middle varchar2(50) 
); 

insert into testtab values ('Joe', 'Jones', 'A'); 
insert into testtab values ('Joe', 'Smith', 'A'); 
insert into testtab values ('Steve', 'Jones', 'B'); 
insert into testtab values ('Axl', 'Rose', 'C'); 
insert into testtab values ('Phil', 'McCracken', 'D'); 
commit; 

創建過程：

CREATE OR REPLACE procedure ECDATA.get_testtab_rows 
(i_name_first in varchar2 default null, 
i_name_last in varchar2 default null, 
i_name_middle in varchar2 default null, 
o_cursor out sys_refcursor 
) as 

    v_result_cur sys_refcursor; 

begin 

    open v_result_cur for 
     select * from testtab 
     where name_first like nvl(i_name_first, '%') 
     and name_last like nvl(i_name_last, '%') 
     and name_middle like nvl(i_name_middle, '%') 
    ; 

    o_cursor := v_result_cur; 

end; 
/

然後調用它像這樣：

declare 

    v_cur sys_refcursor; 
    testtab_rec testtab%rowtype; 

begin 

    get_testtab_rows(i_name_last=>'Jones', o_cursor=>v_cur); 
    loop 

     fetch v_cur into testtab_rec; 
     exit when v_cur%notfound; 
     dbms_output.put_line(testtab_rec.name_first || ' ' || testtab_rec.name_middle || ' ' || testtab_rec.name_last); 

    end loop; 

exception 
    when others then raise; 
end;