Employees learn a lot about an employer's business and sometimes a business wishes to protect its confidential information from competitors. This is a valid and real concern, but beware the EMPLOYMENT AGREEMENT!
As some already know, employment agreements are generally void as against public policy in California. What you really CAN protect are trade secrets and intellectual property. The difference is that one restrains the valid exercise of an employee (or former employee) in seeking business opportunities (VOID) and the other preserves the valuable business knowledge that a company builds over time and prevents a former employee from disclosing this knowledge to others (VALID).
Look into ways you can protect your business property - your business acumen has taken years to develop, refine and teach. But remember, employment agreements are void and likely unenforceable.