写一个isnull函数,实现sql server函数isnull的功能:CREATE OR REPLACE FUNCTION IsNull(vString varchar2,vIfNullValue varchar2 default null) return varchar2 as BEGIN dbms_output.put_line(nvl(vIfNullValue,-1)); if nvl(vIfNullValue,'-1')='-1' then dbms_output.put_line('second value is null'); if nvl(vString,'-1')='-1' then return 'TRUE'; else return 'FALSE'; end if; else dbms_output.put_line('Second value is not null'); return nvl(vString,vIfNullValue); end if; exception when others then raise_application_error('-20000',sqlerrm); END;
BEGIN
dbms_output.put_line(nvl(vIfNullValue,-1));
if nvl(vIfNullValue,'-1')='-1' then
dbms_output.put_line('second value is null');
if nvl(vString,'-1')='-1' then
return 'TRUE';
else
return 'FALSE';
end if;
else
dbms_output.put_line('Second value is not null');
return nvl(vString,vIfNullValue);
end if;
exception
when others then
raise_application_error('-20000',sqlerrm);
END;