Question

What is the best way to handle optional parameter if null value is passed in select query in oracle

E.g. select * from emp where deptno = 10 and empno in (7782,7934)

In above query, if user will not select any empno then it should fetch all records where deptno = 10

Answer 1

Here is a little bit dirty solution for your problem if you just want to instert the value into the string:

SELECT *
FROM emp
WHERE
    deptno = 10
AND (empno IN (%user_input%,%not_used_value%)
OR   COALESCE(%user_input%,NULL) IS NULL);

Here %user_input% is a placeholder for values, selected by user and %not_used_value% is empno id, which is never used.

So, the resulting query could look like this:

SELECT *
FROM emp
WHERE
    deptno = 10
AND (empno IN (7782,7934,-999)
OR   COALESCE(7782,7934,NULL) IS NULL);