Reflexion in PLSQL?

Sie müssen ANYTYPE verwenden um die ANYDATA zu beschreiben und stellen Sie sicher, dass der Typ korrekt ist. Dann können Sie mit piecewise auf das Attribut zugreifen und getVarchar2 .

Der größte Teil des Codes unten dient der Überprüfung des Typs, was Sie nicht benötigen, wenn Sie sich keine Gedanken über Typsicherheit machen.

Funktion zur Rückgabe des Werts:

create or replace function get_first_attribute(
    p_anydata in out anydata --note the "out" - this is required for the "piecewise"
) return varchar2 is
    v_typecode pls_integer;
    v_anytype anytype;
begin
    --Get the typecode, and the ANYTYPE
    v_typecode := p_anydata.getType(v_anytype);

    --Check that it's really an object
    if v_typecode = dbms_types.typecode_object then
        --If it is an object, find the first item
        declare
            v_first_attribute_typecode pls_integer;
            v_aname          varchar2(32767);
            v_result         pls_integer;
            v_varchar        varchar2(32767);
            --Variables we don't really care about, but need for function output
            v_prec           pls_integer; 
            v_scale          pls_integer;
            v_len            pls_integer;
            v_csid           pls_integer;
            v_csfrm          pls_integer;
            v_attr_elt_type  anytype;
        begin
            v_first_attribute_typecode := v_anytype.getAttrElemInfo(
                pos            => 1, --First attribute
                prec           => v_prec,
                scale          => v_scale,
                len            => v_len,
                csid           => v_csid,
                csfrm          => v_csfrm,
                attr_elt_type  => v_attr_elt_type,
                aname          => v_aname);

            --Check typecode of attribute
            if v_first_attribute_typecode = dbms_types.typecode_varchar2 then
                --Now that we've verified the type, get the actual value.
                p_anydata.piecewise;
                v_result := p_anydata.getVarchar2(c => v_varchar);

                --DEBUG: Print the attribute name, in case you're curious
                --dbms_output.put_line('v_aname: '||v_aname);

                return v_varchar;
            else
                raise_application_error(-20000, 'Unexpected 1st Attribute Typecode: '||
                    v_first_attribute_typecode);
            end if;
        end;
    else
        raise_application_error(-20000, 'Unexpected Typecode: '||v_typecode);
    end if;
end;
/

Typen:

create or replace type Person_type as object (fname varchar2(10), lname varchar2(10));

create or replace type other_type as object (first_name varchar2(10), poetry clob);

Testlauf:

declare
    --Create records
    v_type1 person_type := person_type('Ford', 'Prefect');
    v_type2 other_type := other_type('Paula', 'blah blah...');
    v_anydata anydata;
begin
    --Convert to ANYDATA.
    --Works as long as ANYDATA is an object with a varchar2 as the first attribute.
    v_anydata := anydata.convertObject(v_type1);
    dbms_output.put_line(get_first_attribute(v_anydata));

    v_anydata := anydata.convertObject(v_type2);
    dbms_output.put_line(get_first_attribute(v_anydata));
end;
/

Ausgaben:

Ford
Paula