PostgreSQL Example – How to do Self Join Table

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Self Join Table

Create Table Of Adventurers

- Create table called adventurers
CREATE TABLE adventurers (
    - string variable
    name varchar(255),
    - integer variable
    age int,
    - string variable
    child_of varchar(255)
)

Insert Rows Into Adventurers Table


INSERT INTO adventurers (name, age, child_of)
VALUES ('Dallar Woodfoot', 25, NULL),
       ('Cordin Garner', 29, NULL),
       ('Keat Garner', 24, 'Cordin Garner'),
       ('Colbat Nalor', 124, NULL)

Inner Join Tables


- Select name of copy1 and name of copy2 (renamed "parent")
SELECT copy1.name, copy2.name as parent
- Where copy1 and copy2 are identical copies of the adventurers table
FROM adventurers copy1, adventurers copy2
- Merge copy1 and copy2 where the name of copy1 matches the name of child_of field in copy2
WHERE copy1.name = copy2.child_of

<!DOCTYPE html>

name parent
Cordin Garner Keat Garner

Python Example for Beginners

Two Machine Learning Fields

There are two sides to machine learning:

  • Practical Machine Learning:This is about querying databases, cleaning data, writing scripts to transform data and gluing algorithm and libraries together and writing custom code to squeeze reliable answers from data to satisfy difficult and ill defined questions. It’s the mess of reality.
  • Theoretical Machine Learning: This is about math and abstraction and idealized scenarios and limits and beauty and informing what is possible. It is a whole lot neater and cleaner and removed from the mess of reality.

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