সঠিক উত্তর হচ্ছে: ১৯৭০ সালে
ব্যাখ্যা: A relational database is a digital database based on the relational model of data, as proposed by E. F. Codd in 1970. A software system used to maintain relational databases is a relational database management system (RDBMS). Many relational database systems have an option of using the SQL (Structured Query Language) for querying and maintaining the database