Dynamic PL/SQL query, how to ignore null parameters?

问题

I have a PL/SQL procedure with multiple parameters. When a webapp calls the procedure, if it's not using a certain parameter, it passes is as null, ie

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

I want to make an SQL query where I include the given parameters in the WHERE clause only if the parameter is not null. Is there a way to achieve this in an elegant way, other than building the SQL query in a string and then opening the cursor for that string, like this

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

回答1:

I have answered a similar question on dba.stackexchange.com

回答2:

You can code it all into a single select

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

回答3:

Create a test table:

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;

Create your procedure:

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;
/

Then call it like this:

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;

来源：https://stackoverflow.com/questions/4932276/dynamic-pl-sql-query-how-to-ignore-null-parameters

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sql

Oracle

dynamic

plsql