Conditional OR joins in SQL query returns duplicate rows

Scenario: Whenever I have a particular OR condition join in my query, I get a duplicated record. The case is when the two join conditions before and after OR are satisfied.

SELECT A.Column1,A.Column2, Name, Address FROM A, B
WHERE (
(A.COLUMN1 = B.COLUMN1) OR (A.COLUMN2  = B.COLUMN2)
)

Cause: Imagine there are rows in A and B that satisfy the two join conditions used in OR, In such a scenario the database will return two rows with same value.

Here as per the query, for row 'Athul' in Table A, both the join conditions match with B and hence will return below output resultset,

As you can see in the result above, 'Athul' is resulted twice.  However for the second recrod

Solution: This can be avoided by using a LEFT join instead of an OR join condition. Do not consider using DISTINCT as it is a fairly cost consuming alternative.

[Solved] Oracle SQL Developer JVM not Found Error

Scenario: Setting up Oracle SQL Developer for the first time from inside Database home. The first time you try to run SQLDeveloper.exe you will be prompted for a JDK bin path. 

At this step you might face an error as below,

Unable to find Java Virtual Machine error

Cause: The java path defined is a 64bit JDK.

Resolution: Install a new 32bit JDK and then open the sqldeveloper.conf file from app/product/dbhome_1/sqldeveloper/sqldeveloper/bin and delete the JAVA_HOME entry as below,

Changing JavaHome path

After deleting run the SQLDeveloper.exe file and again you will be prompted for a JDK bin path. Now give the path to the new 32bit JDK you just installed. This will make SQLDeveloper run in your machine.