1  RDBMS

1.1 Database Management System (DBMS)

DBMS guarantees compliance with the ACID paradigm. This compliance ensures that in a multi-user environment, all changes made within a single transaction adhere to the following principles:

  • Atomic: either all changes take place or none does.

  • Consistent: changes transform the database from one valid state to another valid state.

  • Isolated: transactions of different users working at the same time will not affect each other.

  • Durable: the database retains committed changes even if the system crashes afterward.

1.2 Relational Database Management System (RDBMS)

  • A relational DBMS is an implementation of data stores according to the design rules of the relational model.

  • This approach allows operations on data based on relational algebra, including projections, selections, joins, and set operations (union, difference, intersection, etc.).

  • Together with Boolean algebra (AND, OR, NOT, etc.) and other mathematical concepts, relational algebra builds up a complete mathematical system with basic operations, complex operations, and transformation rules between the operations.

  • To connect a database, minimal requirement may include: user name, password, database name, host, port etc.

1.3 SQL History

  • Source: Wikipedia

  • SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce in the early 70s.

  • Initially, the pre-release version of SQL was called SEQUEL (Structured English Query Language)

  • IBM released the first version in 1981 and called it SQL (Structured Query Language)

  • SQL became a standard of the American National Standards Institute (ANSI) in 1986

  • It became the standard of the International Organization for Standardization (ISO) in 1987.

  • Since then, several revisions of the standard have been made, introducing new commands and support for technologies such as Java, XML, and regular expressions.

  • The standards are also modified by different RDBMS engines.