Cheet Sheet – SQL 🛢️

I am sure you can find cheet sheets about sql from many sources but I hope that having all the examples and exercises in one place will be useful for you. 🌍

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Basic SQL Commands

Command	Description
SELECT	Retrieves data from a table.
FROM	Specifies the table to retrieve data from.
WHERE	Filters records based on conditions.
INSERT INTO	Inserts new records into a table.
UPDATE	Updates existing records in a table.
DELETE	Deletes records from a table.

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Table Operations

Command	Description
CREATE TABLE table_name	Creates a new table.
DROP TABLE table_name	Deletes an existing table.
ALTER TABLE table_name	Modifies an existing table (e.g., add/drop columns).
TRUNCATE TABLE table_name	Deletes all rows from a table but keeps its structure.

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Data Selection and Filtering

Command	Description
SELECT * FROM table_name	Selects all columns from a table.
SELECT column1, column2	Selects specific columns from a table.
WHERE condition	Filters records based on conditions (e.g., age > 30).
ORDER BY column_name	Sorts records by a specified column.
GROUP BY column_name	Groups records by a specified column.
HAVING condition	Filters grouped records.
DISTINCT	Returns unique values in a column.

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Join Operations

Command	Description
INNER JOIN	Returns matching records from both tables.
LEFT JOIN	Returns all records from the left table and matching records from the right.
RIGHT JOIN	Returns all records from the right table and matching records from the left.
FULL OUTER JOIN	Returns all records from both tables, whether they match or not.

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Functions

Function	Description
COUNT(column_name)	Counts the number of rows.
SUM(column_name)	Returns the sum of a numeric column.
AVG(column_name)	Returns the average value of a numeric column.
MAX(column_name)	Returns the maximum value in a column.
MIN(column_name)	Returns the minimum value in a column.

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Data Manipulation

Command	Description
INSERT INTO table_name	Adds a new record.
VALUES (value1, value2)	Specifies values for the new record.
UPDATE table_name	Updates existing records in a table.
SET column_name = value	Specifies the columns and values to update.
DELETE FROM table_name	Deletes records from a table.
WHERE condition	Adds a condition for the deletion.

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SQL Operators

Operator	Description
=	Equals
<> or !=	Not equals
< or >	Less than / Greater than
<= or >=	Less than or equal / Greater than or equal
BETWEEN	Specifies a range of values
LIKE	Matches a pattern
IN	Matches any value in a list
IS NULL	Finds NULL values
AND, OR, NOT	Combines multiple conditions

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