Quick SQL guide and cheat sheet: Essential Commands

#sql

The guide simplifies SQL, focusing on commonly used commands for effective data handling. You can also download an extensive SQL cheat sheet here.

Key SQL commands include:

DML

SELECT, INSERT, UPDATE, DELETE

Retrieve data: SELECT name FROM employees WHERE department = 'Sales';.
Add data: INSERT INTO employees (name, department) VALUES ('Jane', 'HR');.

DDL

CREATE, ALTER, DROP

Create new table: CREATE TABLE projects (id INT, title VARCHAR(100));.
Modify table: ALTER TABLE projects ADD budget DECIMAL;.

FAQ

What is a subquery?
A query nested inside another query, useful for complex data retrievals.

How does transaction control work?
Commands like COMMIT and ROLLBACK manage changes in database transactions.

How can I improve SQL query performance?
Optimize queries by using indexes, avoiding wildcard selectors, and refining joins to increase database performance.

What are SQL transaction control commands?
Transaction control commands like COMMIT, ROLLBACK, and SAVEPOINT manage changes, ensuring data integrity during transactions.

Conclusion

This SQL cheat sheet is a quick reference for routine SQL tasks, suited for beginners and experienced users alike. For more detailed information, check out the article SQL Cheat Sheet: The Ultimate Guide to All Types of SQL JOINS.