create or replace function min_parameter(val1 int,val2 int,val3 int) return int  is
begin
if val1<val2 and val1<val3 
then 
return 'min_value= '||to_char(val1);
endif;
elsif val2<val1 and val2<val3 
then
return 'min_value='||to_char(val2);
endif;
elsif val3<val1 and val3<val2
then
return 'min_value=' ||to_char(val3);
endif;
end;

create or replace function min_parameter(val1 int,val2 int,val3 int) return int is
begin
if val1<val2 and val1<val3 
then 
return 'min_value= '||to_char(val1);
end if;
elsif val2<val1 and val2<val3 
then
return 'min_value= '||to_char(val2);
end if;
elsif val3<val1 and val3<val2
then
return 'min_value= '||to_char(val3);
end if;
end;

7/7       PLS-00103: Encountered the symbol "VAL2" when expecting one of the following:     := . ( @ % ; The symbol ":=" was substituted for "VAL2" to continue. 
8/1       PLS-00103: Encountered the symbol "THEN" when expecting one of the following:     . ( * @ % & - + ; / at mod remainder rem <an exponent (**)>    and or || multiset 
10/5      PLS-00103: Encountered the symbol "IF" when expecting one of the following:     ; <an identifier> <a double-quoted delimited-identifier>    current delete exists prior <a single-quoted SQL string> 

create or replace function min_parameter(val1 int,val2 int,val3 int) return varchar2 is
begin
if val1<val2 and val1<val3 
then 
return 'min_value= '||to_char(val1);
elsif val2<val1 and val2<val3 
then
return 'min_value= '||to_char(val2);
elsif val3<val1 and val3<val2
then
return 'min_value= '||to_char(val3);
end if;
end;

BEGIN
    --DBMS_OUTPUT.enable;
    DBMS_OUTPUT.put_line( min_parameter(257,555,161));
END;

select least(5, 6, 7) as t1 from dual