The term expert is commonly used. In reality , if you have a 5-10 yrs experience you could call yourself an expert. It's the type of experience you've had which matters most.
- Hands-on experience - The path to SQL Server expertise is composed of working on real-world, mission-critical SQL Server databases. No amount of at-home learniing can compare with the learning from working on a real production database. Get this type of experience at all costs
- Quality experience - There is a wide variation in the quality of experience in the SQL Server spectrum. Not all experience is rated the same, and a challenging high-performance database job (such as an OLTP ) will provide far more expertise exposure than maintaining a stable database.
- Broad experience - A broad base with many different types of SQL Server database is essential for developing expert status. I've been in companies with over 10 DBA's, where job duties are highly niche such as security administration, or replication. On the other hand, a single DBA managing a server farm is more likely to get a broader range of experience. The best place to get experience is as a SQL Server consultant where you are exposed to dozens of
novel databases each year. A high performing SQL Server DBA will have experience
in many areas including OLTP, OLAP and batch databases.