database

3 of 200 yen apples, 2 of 150 yen bread, 8 of 100 yen coffee

We use tables to store data. Like a spreadsheet, Excel on Windows or Google Sheets, or Numbers on Mac.

flat-file database

A text file to store data in plain text.

Comma separated values (CSV)

Store the data line by line, with each line representing a record. Each field is separated by a comma.

amount,price,name
3,200,Apple
2,150,Bread
8,100,Coffee

The first line, or first row, is the header. It defines the name of each column.

relational database

Definition: A database that stores data in tables, with relationships between the tables.

Usually you can import CSV files into a relational database.

SQL (Structured Query Language)

SQL (pronounced “sequel” or “S-Q-L”) is a language used to communicate with relational databases. It is used to Create, Read, Update, and Delete data in the database.

create INDEX to make the query faster

• Database
  • A container (a file or many files) to store organized data.
• DBMS(Database Management System)
  • the database software, like the Excel software to data.xlsx
• Table
  • a structured list of data of a specific type
  • In a database, table name is unique
• Schema
  • information about database and table layout and properties.
• Column
  • a single field in a table. all tables are made up of one or more columns.
  • break data into multiple columns correctly, like “city”, “state”, “street”, instead of “address”, or save both