SQL.txt

SQL, Databases, and PostgreSQL | Section Summary

SQL - Standard Query Language - is a programming language used to communicate with a database.

A database is a structured collection or table of data.

A database record represents a collection of fields or elements through an entry.

A query allows us to ask the database a question about its data and grab relevant information.

A database schema outlines what attributes correspond to data entries for a particular table.

PostgreSQL (pronounced post-gress-QL) is a system that allows us to interact with an SQL relational database.

Advantages to SQL:

SQL allows to access many records of data within a single command.

SQL allows to interact with our data in multiple ways: insertion, queries, updates, and deletions.

SQL is widely adopted in the programming community and software engineering industry.

The relational model is an approach to organizing data where all f the data is represented by rows and grouped into relations.

Rows may also be called tuples.

SQL has a declarative syntax which makes statements look like English-readable sentences because it describes what the program must accomplish in order to solve a problem.

SQL commands:

Use CREATE TABLE to make a table. INSERT INTO <table> VALUES to insert entries into <table>.

Use the SELECT keyword to query data. FROM to specify a database.

Use the WHERE clause to limit data based on a condition. Use LIMIT <number> to limit the resulting queries to the top <number> results.

Use JOIN … ON to combine two tables based on a given condition.