Codd's Rules No 05: A Single Language is Used to Communicate with the DBMS

• There must be a single language that handles all communication with the database management system
• The language must support relational operations with respect to:

1. data modification, i.e., SELECT, INSERT, UPDATE, DELETE
2. data definition, i.e., CREATE, ALTER, DROP
3. administration, i.e., GRANT, REVOKE, DENY, BACKUP, RESTORE

• Structured Query Language (SQL) is the in practice standard for a relational database language
• SQL is a 'non-procedural' or 'declarative' language; it allows users to express what they want from the RDBSMS without specifying the details about where it's located or how to get it