This cheat sheet provides a quick reference for some of the most commonly used SQL operations, including basic data retrieval, filtering and sorting, data modification, and aggregation. Whether you are a beginner or an experienced SQL user, this cheat sheet can serve as a handy reminder of the syntax and functionality of the SQL language.
Basic Operations:
SELECT: Retrieve data from a table
Syntax: SELECT column1, column2, ... FROM table_name;
WHERE: Filter data based on conditions
Syntax: SELECT column1, column2, ... FROM table_name WHERE condition;
LIMIT: Limit the number of returned rows
Syntax: SELECT column1, column2, ... FROM table_name LIMIT number_of_rows;
ORDER BY: Sort data in ascending or descending order
Syntax: SELECT column1, column2, ... FROM table_name ORDER BY column_name [ASC | DESC];
UPDATE: Modify data in a table
Syntax: UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition;
DELETE: Remove data from a table
Syntax: DELETE FROM table_name WHERE condition;
INSERT INTO: Add data to a table
Syntax: INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);
Joining Tables:
INNER JOIN: Retrieve data that matches in both tables
Syntax: SELECT column1, column2, ... FROM table1 INNER JOIN table2 ON condition;
LEFT JOIN (or LEFT OUTER JOIN): Retrieve all data from the left table and matching data from the right table
Syntax: SELECT column1, column2, ... FROM table1 LEFT JOIN table2 ON condition;
RIGHT JOIN (or RIGHT OUTER JOIN): Retrieve all data from the right table and matching data from the left table
Syntax: SELECT column1, column2, ... FROM table1 RIGHT JOIN table2 ON condition;
FULL OUTER JOIN: Retrieve all data from both tables
Syntax: SELECT column1, column2, ... FROM table1 FULL OUTER JOIN table2 ON condition;
Aggregate Functions:
COUNT: Count the number of rows
Syntax: SELECT COUNT(column_name) FROM table_name;
SUM: Calculate the sum of values in a column
Syntax: SELECT SUM(column_name) FROM table_name;
AVG: Calculate the average of values in a column
Syntax: SELECT AVG(column_name) FROM table_name;
MIN: Retrieve the minimum value in a column
Syntax: SELECT MIN(column_name) FROM table_name;
MAX: Retrieve the maximum value in a column
Syntax: SELECT MAX(column_name) FROM table_name;
GROUP BY: Group data by a column and apply aggregate functions to each group
Syntax: SELECT column1, SUM(column2), ... FROM table_name GROUP BY column1;
This cheat sheet provides a basic understanding of SQL and covers the most commonly used operations. However, this is not an exhaustive list and SQL has many other features and functions.
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