Can I use a query by itself as a filter in pl/sql?

user_8050868 0
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I know I didn't make it clear in the question title. Let me explain.

Say I have a Table SOURCE_TABLE with 1 column that looks like this:

Filter 
------------------|
Name='John' 
Surname = 'Smith' 
Age = '25'

And I want to use this table as a filter. Like below:

SELECT * FROM TARGET_TABLE WHERE (SELECT FILTER FROM SOURCE_TABLE)

I heard maybe evaluate function could help me but to be honest I couldn't understand how.

Do you know any method that I can use a column as my filter source like above?

Edit1:

DECLARE 
    my_filter VARCHAR2(100); 
    my_query VARCHAR2(500); 
BEGIN 
    my_query := 'SELECT FILTER FROM SOURCE_TABLE WHERE ROWNUM=1'; 
    EXECUTE IMMEDIATE my_query INTO my_filter; 
    EXECUTE IMMEDIATE 'SELECT * FROM TARGET_TABLE WHERE '|| my_filter; 
END;

@Sujitmohanty30 I have come up with the above after learning EXECUTE IMMEDIATE. But there is a problem I stumble upon. This needs to be dynamic regarding to the end result and i want to see the result of the select query at the end.

dynamic-sql plsql oracle sql
1 Answers

Let's say we have these 2 tables:

create table TARGET_TABLE(name varchar2(30), surname varchar2(30));
insert into TARGET_TABLE(name,surname) values ('John', 'Doe');
insert into TARGET_TABLE(name,surname) values ('Ann', 'Smith');
insert into TARGET_TABLE(name,surname) values ('Steven', 'Feuerstein');
insert into TARGET_TABLE(name,surname) values ('Steven', 'King');
commit;

create table SOURCE_TABLE(filter) as
select q'[name='John']' from dual union all
select q'[name='Ann']' from dual union all
select q'[name='Steven' and surname='King']' from dual union all
select q'[surname='Feuerstein']' from dual;

Then you can use xmltable and dbms_xmlgen.getXMLtype to get such rows dynamically:

https://dbfiddle.uk/?rdbms=oracle_18&fiddle=72abdf18b149cf30882cb4e1736c9c33

select *
from SOURCE_TABLE
    , xmltable(
        '/ROWSET/ROW'
        passing dbms_xmlgen.getXMLtype('select * from TARGET_TABLE where '|| SOURCE_TABLE.filter)
        columns 
          name    varchar2(30) path 'NAME',
          surname varchar2(30) path 'SURNAME'
        ) x;

Results:

FILTER                           NAME                           SURNAME
-------------------------------- ------------------------------ ------------------------------
name='John'                      John                           Doe
name='Ann'                       Ann                            Smith
name='Steven' and surname='King' Steven                         King
surname='Feuerstein'             Steven                         Feuerstein
user_4291000
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