Oracle Dynamic delete statements with DECODE Function - oracle

Question

Hi I have the following procedure:
create or replace procedure
SP_DELETE_FROM_TABLE(pTableName in VARCHAR2, pFieldName in VARCHAR2,
pFieldValue in VARCHAR2,pFieldType in VARCHAR2) is
querystring VARCHAR2(500);
begin
queryString := 'DELETE FROM ' ||pTableName||
' WHERE '||pFieldName ||' = DECODE(:pFieldType,integer,:pFieldValue)' ;
EXECUTE IMMEDIATE queryString USING pFieldType,pFieldValue;
end SP_DELETE_FROM_TABLE;
all my Parameters are of Type VARCHAR2, What I am trying to do is: When I call the procedure with the following values ('users_table','users_id','11','integer')
so by using DECODE I would like to check if pFieldValue is of type pFieldTypeand if yes return pFieldValue
so if pFieldValue is:11 and pfieldType is:integer it should delete users_id 11 if fieldType is string do nothing..

Answer 1

I'd create a function that checks parameter has correct type
and then use it in main procedure
--main procedure
create or replace procedure SP_DELETE_FROM_TABLE(pTableName in VARCHAR2, pFieldName in VARCHAR2,pFieldValue in VARCHAR2,pFieldType in VARCHAR2) is
querystring VARCHAR2(500);
begin
if 'Y' = is_type_correct(pFieldValue, pFieldType ) then
queryString := 'DELETE FROM ' ||pTableName|| ' WHERE '
||pFieldName ||' = :pFieldValue';
EXECUTE IMMEDIATE queryString USING pFieldValue;
end
else
null; --incorrect type and parameter, do nothing
end;
end SP_DELETE_FROM_TABLE;
--check function
CREATE OR REPLACE FUNCTION is_type_correct( p_val IN VARCHAR2, p_type varchar2 )
RETURN VARCHAR2 DETERMINISTIC PARALLEL_ENABLE
IS
l_num NUMBER;
l_date date;
BEGIN
if 'integer' = p_type
then
l_num := to_number( p_val );
elsif 'date' = p_type then
l_date := to_date(p_val, 'YYYY.MM.DD');
elsif 'varchar2' then
null;//do nothing
else
return 'N'; //uknown type
end if;
RETURN 'Y';
EXCEPTION
WHEN value_error THEN
RETURN 'N';
END is_number;

Answer 2

Just try to convert a string to a number, and when an exception occurs, do nothing:
querystring VARCHAR2(500);
some_number number;
begin
some_number := to_number( pFieldValue ); /* trying to convert to a number */
queryString := 'DELETE FROM ' ||pTableName||
' WHERE '||pFieldName ||' = :x' ;
EXECUTE IMMEDIATE queryString USING some_number;
EXCEPTION
WHEN VALUE_ERROR THEN null; /* do nothing when pFieldValue is not a number*/
end SP_DELETE_FROM_TABLE;