Title: Merge Tables
Slug: merge_tables
Summary: Merge tables in SQL.
Date: 2016-05-01 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
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 (234, 'Bill James', 22, 'M', 'Santa Rosa', 0);
INSERT INTO criminals VALUES (632, 'Stacy Miller', 23, 'F', 'Santa Rosa', 0);
INSERT INTO criminals VALUES (621, 'Betty Bob', NULL, 'F', 'Petaluma', 1);
INSERT INTO criminals VALUES (162, 'Jaden Ado', 49, 'M', NULL, 0);
INSERT INTO criminals VALUES (901, 'Gordon Ado', 32, 'F', 'Santa Rosa', 0);
INSERT INTO criminals VALUES (512, 'Bill Byson', 21, 'M', 'Santa Rosa', 0);
INSERT INTO criminals VALUES (411, 'Bob Iton', NULL, 'M', 'San Francisco', 0);
-- Create a table of crimes
CREATE TABLE crimes (cid, crime, city, pid_arrested, cash_stolen);
INSERT INTO crimes VALUES (1, 'fraud', 'Santa Rosa', 412, 40000);
INSERT INTO crimes VALUES (2, 'burglary', 'Petaluma', 234, 2000);
INSERT INTO crimes VALUES (3, 'burglary', 'Santa Rosa', 632, 2000);
INSERT INTO crimes VALUES (4, NULL, NULL, 621, 3500);
INSERT INTO crimes VALUES (5, 'burglary', 'Santa Rosa', 162, 1000);
INSERT INTO crimes VALUES (6, NULL, 'Petaluma', 901, 50000);
INSERT INTO crimes VALUES (7, 'fraud', 'San Francisco', 412, 60000);
INSERT INTO crimes VALUES (8, 'burglary', 'Santa Rosa', 512, 7000);
INSERT INTO crimes VALUES (9, 'burglary', 'San Francisco', 411, 3000);
INSERT INTO crimes VALUES (10, 'robbery', 'Santa Rosa', 632, 2500);
INSERT INTO crimes VALUES (11, 'robbery', 'Santa Rosa', 512, 3000);
Out[2]:
In [3]:
%%sql
-- Select everything
SELECT *
-- Left table
FROM criminals
-- Right table
INNER JOIN crimes
-- Merged on `pid` in the criminals table and `pid_arrested` in the crimes table
ON criminals.pid=crimes.pid_arrested;
Out[3]:
In [4]:
%%sql
-- Select everything
SELECT *
-- Left table
FROM criminals
-- Right table
LEFT JOIN crimes
-- Merged on `pid` in the criminals table and `pid_arrested` in the crimes table
ON criminals.pid=crimes.pid_arrested;
Out[4]:
Note: FULL OUTER and RIGHT JOIN are not shown here because they are not supported by the version of SQL (SQLite) used in this tutorial.