Which of the following options are relational databases
A.MySQL
B.Oracle
C.SQL Server
D.PostgreSQL
Answer: ABCD
Pure memory question, just remember it.
Basic concepts of relational database
Relational model : The relational model regards the world as composed of entities (Entity) and connections (Relationship). Entities are things that exist objectively in reality and can be distinguished from each other.
Relational database : A database based on the relational model is a relational database. In a given application field, the collection of all entities and the links between entities constitutes a relational database.
P.S. Micro-authentication is useless, it's too basic. You can get by with a monkey who can only type.