Database and DBMS
Database(DB) is a set of all data in a computer. Databases are everywhere, from a data center and even to a smartphone.
Database Management System(DBMS) is a software that can effeciently manage database. There are 3 reasons that the DBMS is needed.
- Productivity: Enhance productivity while developing a system. Basic functions such as searching, adding, removing and updating are provided by DBMS.
- Functionality: DBMS provides many functions that can control DB. It also contains handling muliple requests, and customizing.
- Reliability: By using multiple DBMS computers, scalability and load balancing can be implemented. It is called clustering or scaling out.
SQL
SQL is a language for conversations with DBMS. Although there are many types of databases, SQL is used to control RDBMS(Relational DBMS).
SQL command can be divided into 3 types.
- DML(Data Manipulation Language): The most basic command set of SQL. Used when adding, removing and updating data.
- DDL(Data Definition Language): Used to make or delete database object.
- DCL(Data Control Language): Control transaction or data access authority.
All images, except those with separate source indications, are excerpted from lecture materials.
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