What the Heck is ORA-01795?

This is the error message that you should not be seeing it. However, when people use dummy tools to generate the SQL queries, they will often encounter this issue. Oracle does not let over 1000 values inside IN functions. In Order to avoid this situation, we will need to build inner queries. To make this explanation more clear lets do the lab exercise to demo this problem and solution.

Lab Exercise:  

Let's  re-create a problem and then put a fix to it..

Problem:

SELECT * 

FROM   dept 

WHERE  fname IN ( 'NAME1', 'NAME2',............... 'NAME1000', 'Name1002' ); 

Result:

Database Error: ORA-01795: maximum number of expressions in a

list is 1000

Solution:

SELECT * 

FROM   dept 

WHERE  name IN (SELECT fname 

                FROM   employee); 

What is the take home from this exercise? Write your own damn query! Be a MAN!!!