I did it successfully (OCA & OCP) then I built ERP system for Electronic infrastructure company, I was working for then (alone) and the purpose was connecting and integrating the head office with the different work sites inside and outside Egypt, Actually my strategy is to Understanding project requirements, perform initial design then development according to project Requirements and recommends improvements, Analyze and troubleshoot system issues in a timely manner and perform bug Fixes, Implement rules for data integrity and data migration, this system includes the following departments: HR, procurement, finance (Time Sheet for workers, engineers), Logistics (finished with a percentage of 20%), recruitments process, I was using oracle tools (Oracle Database 10g- Oracle forms- PL/SQL – Oracle Java Initiator), statistics (77 Tables, 250 Forms, 50 report).