MySQL-001 General Terminologies

11 months ago
Ruian Ding
3 minutes

Database (DB)

A database is a structured collection of data. It can be electronic (stored in a computer system) or physical (like a filing system in an office). In the context of IT and computing, a database typically refers to a data structure that stores information electronically.

Database Management Systems (DBMS)

A special software system designed to help users create and manage databases.

It provides an interface between the data stored in databases and the users or application programs.

App service is telling the DBMS to do the job, instead of interactive with the DB itself directly.

C.R.U.D

It represents the four basic operations that can be performed on data in a database or a data storage system: Create, Read (Retrieve), Update, Delete

  • Create: This operation involves adding new data to the database. For example, in a relational database, this could mean inserting a new row into a table.
  • Read: This operation entails retrieving or reading data from the database. It could be as simple as fetching a single record or as complex as executing a query that filters and sorts a large amount of data.
  • Update: This operation is about modifying existing data in the database. This could involve changing the values of certain fields in a record or several records.
  • Delete: This operation involves removing data from the database. This could mean deleting a single record, a group of records, or even clearing an entire table.

Two Main Types of Databases

Relational Databases – SQL

Relational databases store data in tables, which consist of rows and columns. Each row represents a unique record, and each column represents a field within the record.

  • Relational Database Management Systems (RDBMS)
    • Help users create and maintain a relational database
  • Use the Structured Query Language (SQL)
    • Standardized language for interacting with RDBMS
    • Used to perform C.R.U.D operations, as well as other administrative tasks
    • Used to defined tables and structures

Popular examples include MySQL, PostgreSQL, Oracle, and Microsoft SQL Server.

Non-Relational Databases – NoSQL

NoSQL databases can store data in various formats other than tabular relations. This includes document, key-value, wide-column, and graph formats.

Popular examples include MongoDB (document-based), Redis (key-value store), Cassandra (wide-column store), and Neo4j (graph database).

Database Queries

Database queries are requests to access data from a database. These queries are used to perform various operations on the data stored in the database, such as retrieving specific information, updating records, inserting new data, or deleting existing data.

Queries are a fundamental aspect of interacting with databases, allowing users and applications to manipulate and analyze the data according to their needs.