Title: Selecting Unique Rows
Slug: selecting_unique_rows
Summary: Selecting unique rows in SQL. Date: 2017-01-16 12:00
Category: SQL
Tags: Basics
Authors: Chris Albon

Note: This tutorial was written using Catherine Devlin's SQL in Jupyter Notebooks library. If you have not using a Jupyter Notebook, you can ignore the two lines of code below and any line containing %%sql. Furthermore, this tutorial uses SQLite's flavor of SQL, your version might have some differences in syntax.

For more, check out Learning SQL by Alan Beaulieu.


In [1]:
# Ignore
%load_ext sql
%sql sqlite://
%config SqlMagic.feedback = False

Create Data


In [2]:
%%sql

-- Create a table of criminals
CREATE TABLE criminals (pid, name, age, sex, city, minor);
INSERT INTO criminals VALUES (412, 'James Smith', 15, 'M', 'Santa Rosa', 1);
INSERT INTO criminals VALUES (412, 'James Smith', 15, 'M', 'Santa Rosa', 1);
INSERT INTO criminals VALUES (412, 'James Smith', 15, 'M', 'Santa Rosa', 1);
INSERT INTO criminals VALUES (901, 'Gordon Ado', 32, 'F', 'San Francisco', 0);
INSERT INTO criminals VALUES (512, 'Bill Byson', 21, 'M', 'Petaluma', 0);


Out[2]:
[]

View All Rows

Notice that 'James Smith' appears three times


In [3]:
%%sql

--  Select all
SELECT *

-- From the criminals table
FROM criminals


Out[3]:
pid name age sex city minor
412 James Smith 15 M Santa Rosa 1
412 James Smith 15 M Santa Rosa 1
412 James Smith 15 M Santa Rosa 1
901 Gordon Ado 32 F San Francisco 0
512 Bill Byson 21 M Petaluma 0

View Unique Rows


In [4]:
%%sql

--  Select all unique
SELECT distinct *

-- From the criminals table
FROM criminals


Out[4]:
pid name age sex city minor
412 James Smith 15 M Santa Rosa 1
901 Gordon Ado 32 F San Francisco 0
512 Bill Byson 21 M Petaluma 0