Sample Random Rows From A Table
Create Table Of Superheroes
- Create a table called SUPERHEROES.
CREATE OR REPLACE TABLE SUPERHEROES (
- Column called ALTER_EGO allowing up to 100 characters
"ALTER_EGO" VARCHAR(100),
- Column called BANK_BALANCE allowing 38 digits with 2 after the decimal point
"AGE" NUMBER(3, 0)
);
Insert Rows For Each Superhero
- Insert rows into SUPERHEROES
INSERT INTO SUPERHEROES
- With the values
VALUES
('The Bomber', '24'),
('Mr. Money', '12'),
('Nuke Miner', '59'),
('The Knife', '43'),
('Ninka Baker', '32'),
('Banana Bomber', '34'),
('Augustine', '12'),
('The Kid', '21'),
('The Viking', '291'),
('Skull Hustle', '10');
Sample Where Reach Row Has Chance Of Inclusion
- Select all columns
SELECT *
- From the SUPERHEROES table
FROM SUPERHEROES
- Sample a subset of rows, where each row has a 25% chance of being selected
SAMPLE ROW (25);
ALTER_EGO | AGE |
---|---|
The Bomber | 24 |
Nuke Miner | 59 |
Sample Where N Rows Are Desired
- Select all columns
SELECT *
- From the SUPERHEROES table
FROM SUPERHEROES
- Sample a subset of 3 rows
SAMPLE ROW (3 rows);
ALTER_EGO | AGE |
---|---|
Augustine | 12 |
Mr. Money | 12 |
Ninka Baker | 32 |
Sample With A Need
Seeds improve repeatability, when rerun on the same data, samples using the same need value (e.g. 44
) will return the same rows.
- Select all columns
SELECT *
- From the SUPERHEROES table
FROM SUPERHEROES
- Sample a subset of rows, where each row has a 25% chance of being selected with a seed of 99
SAMPLE ROW (25) SEED (99);
ALTER_EGO | AGE |
---|---|
The Knife | 43 |
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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