In order to become a pl/sql developer, you must have a deep understanding of SQL and pl/sql, as well as the database platform you are working with, such as Oracle, MySQL, or PostgreSQL. You should also possess proficiency in database design and modeling, including normalization, indexing, and constraints; data analysis and manipulation, including joins, subqueries, aggregation, and functions; programming logic and control structures, such as loops, conditions, variables, and exceptions; testing and debugging tools and techniques, such as unit testing, logging, and error handling; performance optimization and tuning techniques, such as explain plans, profiling, and hints; and database security and administration like roles, privileges, and backup and recovery.