Introduction to SQL

Introduction to SQL

Aliasing is used to rename columns

DataFrameas

df

variable

SELECT name AS first_name, year_hired
FROM employees;

Hidden output

Use DISTINCT to make sure there are no repeat values when running SQL code

DataFrameas

df1

variable

SELECT DISTINCT dept_id, year_hired
FROM employees;

A view is a virutal table that is the result of a saved SQL **SELECT **statement When accessed, views automaticaly update in repsonse to updates in the underlying data

DataFrameas

df2

variable

CREATE VIEW employee_hire_years AS
SELECT id, name, year_hired
FROM employees;

PostgreSQL -Free and open-source relational database system -Created at the Univsersity of California, Berkeley -"PostgreSQL" refers to both the PostgreSQL database system and its associated SQL flavor

SQL Server -Has free and paid versions -Created by Microsoft -T-SQL is Microsoft's SQL flavor, used with SQL Server databases.