I have a procedure that handles generic searches submitted by user.
User can enter name, hiredate or salary or stock number.

All the data can be fetched from EMP table except when user enters a "Stock Number". If he does, then query needs to lookup in EMP_ORDERS_DETAILS to search for records that match the stock number. For example, if user entered "DVD100", I would need to find all customers who placed orders with that stock number "DVD100".

Would it best to create another query string for this condition (when user enters this field) that JOINS both table EMP and EMP_ORDER_DETAILS like this

--Add this to declaration
l_query_detail varchar2(512) default 'select * from emp a, emp_order_details b where ...'

--Addd this after begin
if (p_stock_no is NOT NULL) then
l_query := l_query_detail;
end if;

if ( p_stock_no is NOT NULL )
  l_query := l_query ||‘ and stock_no =:p_stock_no'‘;
  l_query := l_query || ‘ and (1=1 or :p_stock_no is null) ‘;
end if;

....continue code below as normal

create or replace procedure my_new_procedure
( p_ename in varchar2 default NULL,
p_hiredate in date default NULL,
p_sal in number default NULL)
l_cursor sys_refcursor;
l_query varchar2(512) default ‘select * from emp’;

cursor l_template is select * from emp;
l_rec l_template%rowtype;
if ( p_ename is NOT NULL )
  l_query := l_query ||‘ where ename like ‘’%’’||:p_ename||’’%’’ ‘;
l_query := l_query ||‘ where (1=1 or :p_ename is null) ‘;
end if;

if ( p_hiredate is NOT NULL )
  l_query := l_query ||‘ and hiredate > :p_hiredate ‘;
  l_query := l_query || ‘ and (1=1 or :p_hiredate is null) ‘;
end if;

if ( p_sal is NOT NULL )
  l_query := l_query || ‘ and sal > :p_sal ‘;
  l_query := l_query || ‘ and (1=1 or :p_sal is null) ‘;
end if;

dbms_output.put_line ( l_query );

open l_cursor for l_query using p_ename, p_hiredate, p_sal;
fetch l_cursor into l_rec;
exit when l_cursor%notfound;
dbms_output.put_line ( l_rec.ename || ‘,’ || l_rec.hiredate || ‘,’ || l_rec.sal );
end loop;
close l_cursor;


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Yes, you are right.
At first time I think on alternate parameter, not combinations.

Next I propose a Complex Query that can combine any number of parameters.
You work with strings, then oracle always need parse your sentence.
Then two solutions are identicals on performance.

Note that you can declare cursors and execute it with "Using" Clause for parameters.

Then cursors are precompiled and Oracle do´nt need parse.
sam15Author Commented:
since the query is not known until compile time, you have to start using a string and then add to it based on user inputs.
But since cursor is using bind variables it should parse only once and run thousands of times later.
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You says have 3 cases, then you can declare 3 cursors and select the apropiate cursor depending on selected parameter.

Also, when your query is not deterministic using parameters do the possibility for Oracle Cache Find Sql Sentences more probable.
You can also define a more complex Sql sentence that allow omited parameter:

SQL> Select codtra,destra,sup,tord,ubtec from r18td 
  2  where   ('&Sup'='NA' or sup='&Sup') and
  3          ('&Tord'='NA' or Tord ='&Tord') and
  4          ('&UbTec'='NA' or UbTec='&UbTec');
old   2: where   ('&Sup'='NA' or sup='&Sup') and
new   2: where   ('JLL'='NA' or sup='JLL') and
old   3:         ('&Tord'='NA' or Tord ='&Tord') and
new   3:         ('WS'='NA' or Tord ='WS') and
old   4:         ('&UbTec'='NA' or UbTec='&UbTec')
new   4:         ('NA'='NA' or UbTec='NA')

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Note that I use SqlPlus to build Sample and it support replacement, not parameters.
I use 'NA' for omited parameters.
When you build a query with parameters, you can code like:

   (pSup is null or pSup=Sup)                       -- Where pSup is a Plsql Var or procedure parameter


   (:pSup is null or :pSup=Sup)                     -- Where I use Oracle.DataAccess Command with BindByName = True
I Built a complex QueryCtl on Vb.Net that allows build Dynamic Query for Oracle and also for memory DataTables.
When I send a query to Oracle, always use Parameters.
It is very important for DataType compatibility and also for special character support ( embebed Quote by sample ).

For this sample, the DataTable Filter or displayed query is:

       "(T.Sup = 'JLL' And (T.Est = '8' Or T.Anulado is not null))"

But Query to Oracle with Parameters is:

       "(T.Sup = :1 And (T.Est = :2 Or T.Anulado is not null))"
sam15Author Commented:
if I have 3 parameters. I would need 6 CURSORS (not 3).

Think of all the combinations you can have (1 only, 2 only, 3 only, 1&2, 2&3, 1&3, 1&2&#).
If you have 4 parameters then you would need 24 cursors if you want to do that way.

sam15Author Commented:
not fully answer question
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