JOIN vs. RIGHT JOIN vs. LEFT JOIN

Extracted from this source

• (INNER) JOIN: Returns records that have matching values in both tables

• LEFT (OUTER) JOIN: Returns all records from the left table, and the matched records from the right table

• RIGHT (OUTER) JOIN: Returns all records from the right table, and the matched records from the left table

• FULL (OUTER) JOIN: Returns all records when there is a match in either left or right table

HAVING vs. WHERE

SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
HAVING condition
ORDER BY column_name(s);

• WHERE: Like if after SELECT xx FROM yy
• HAVING: Only after every GROUP BY, it’s like WHERE but for aggregate functions.

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IS vs =

IS is for alphanumeric values and = is for numbers

test

|name|value|
|pepe| 11	|
|pepa| 5 |
|peepo| 11| 

SELECT name FROM test
WHERE name IS "pep%"

>> pepe,pepa

SELECT name FROM test
WHERE value = 11

>> pepe, peepo