Introduction to databases and persistence
This glossary explains the technical words used in this course. Click on a term to jump to its definition.
A set of 4 rules (Atomicity, Consistency, Isolation, Durability) that guarantee database transactions are processed reliably.
The process of gathering data and summarizing it. For example, calculating the average age of all students or counting how many users are in a system.
The rule that a transaction must happen completely or not at all. It cannot be half-finished.
The software or program that asks for data. In this course, the sqlite3 command line tool is the client. Your JavaScript code can also be a client.
A vertical list in a table that holds a specific type of data (like first_name or age). Also called a Field or Attribute.
A rule applied to a column to ensure data quality. For example, "this email must be unique" or "this age cannot be empty".
Short for Create, Read, Update, Delete. These are the four basic operations you can perform on data.
An organized collection of data stored electronically.
SQL commands used to define the structure of the database, like CREATE TABLE or DROP TABLE.
SQL commands used to manage the data inside the tables, like INSERT, UPDATE, and SELECT.
The guarantee that once data is saved (committed), it stays saved, even if the power goes out.
See Column (above).
A column in one table that links to the Primary Key of another table. It creates a relationship between the two tables.
A special data structure (like a book's index) that helps the database find rows quickly without looking through the whole table.
Refers to the accuracy and consistency of data. "Relational Integrity" means that links between tables (like Foreign Keys) are valid.
An SQL operation that combines rows from two or more tables based on a related column between them.
The process of organizing data to reduce repetition (duplication). This usually involves breaking big tables into smaller, related tables.
The ability of data to survive after the program that created it stops running. The "Persistence Layer" is the part of your code that handles saving and loading data.
A unique identifier for a specific row in a table. No two rows can have the same Primary Key.
A request for information from a database.
Relational Database Management System. Software that manages relational databases (e.g., SQLite, PostgreSQL).
See Row (above).
Another formal name for a Table (see below).
A horizontal line in a table that represents a single item (like one student). Also called a Record or Tuple.
The blueprint or structure of the database. It defines the tables, the columns in each table, and the relationships between them.
A program that runs in the background and listens for requests from a Client (see above).
The standard programming language used to communicate with relational databases.
A collection of related data held in a table format within a database. It consists of columns and rows. Also called a Relation.
A group of SQL commands that are treated as a single unit. Either all of them succeed, or none of them do.
See Row (above).
A virtual table based on the result of a specific query. It does not store data itself but saves the query structure for easy reuse.
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