10 Essential Sql Commands On One Handy Cheat Sheet

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As a database administrator or developer, you likely work with SQL (Structured Query Language) on a daily basis. While it's easy to get familiar with the basics, it's not uncommon to find yourself needing to reference specific commands or syntax. That's why we've put together this handy cheat sheet of 10 essential SQL commands that you can keep coming back to.

Why SQL Commands Matter

SQL is a powerful language that allows you to manage and manipulate data in relational databases. Whether you're working with MySQL, PostgreSQL, Microsoft SQL Server, or another database management system, understanding the basics of SQL is crucial. With these essential commands, you'll be able to perform common tasks, troubleshoot issues, and optimize your database performance.

1. SELECT Statement

The SELECT statement is used to retrieve data from one or more tables in a database. The basic syntax is:

SELECT column1, column2,...
FROM tablename;

For example:

SELECT * FROM customers;

This will retrieve all columns (*) from the customers table.

Image of SELECT Statement

2. INSERT INTO Statement

The INSERT INTO statement is used to add new data to a table. The basic syntax is:

INSERT INTO tablename (column1, column2,...)
VALUES (value1, value2,...);

For example:

INSERT INTO customers (name, email, phone)
VALUES ('John Doe', 'johndoe@example.com', '123-456-7890');

This will insert a new row into the customers table with the specified values.

Image of INSERT INTO Statement

3. UPDATE Statement

The UPDATE statement is used to modify existing data in a table. The basic syntax is:

UPDATE tablename
SET column1 = value1, column2 = value2,...
WHERE condition;

For example:

UPDATE customers
SET name = 'Jane Doe', email = 'janedoe@example.com'
WHERE id = 1;

This will update the row with id = 1 in the customers table with the specified values.

Image of UPDATE Statement

4. DELETE Statement

The DELETE statement is used to delete existing data from a table. The basic syntax is:

DELETE FROM tablename
WHERE condition;

For example:

DELETE FROM customers
WHERE id = 1;

This will delete the row with id = 1 from the customers table.

Image of DELETE Statement

5. CREATE TABLE Statement

The CREATE TABLE statement is used to create a new table in a database. The basic syntax is:

CREATE TABLE tablename (
  column1 datatype,
  column2 datatype,
 ...
);

For example:

CREATE TABLE orders (
  id INT PRIMARY KEY,
  customer_id INT,
  order_date DATE
);

This will create a new table named orders with the specified columns and data types.

Image of CREATE TABLE Statement

6. DROP TABLE Statement

The DROP TABLE statement is used to delete an existing table from a database. The basic syntax is:

DROP TABLE tablename;

For example:

DROP TABLE orders;

This will delete the orders table from the database.

Image of DROP TABLE Statement

7. ALTER TABLE Statement

The ALTER TABLE statement is used to modify the structure of an existing table. The basic syntax is:

ALTER TABLE tablename
ADD/MODIFY/DROP columnname datatype;

For example:

ALTER TABLE customers
ADD COLUMN address VARCHAR(255);

This will add a new column named address with a data type of VARCHAR(255) to the customers table.

Image of ALTER TABLE Statement

8. TRUNCATE TABLE Statement

The TRUNCATE TABLE statement is used to delete all data from a table without logging the individual row deletions. The basic syntax is:

TRUNCATE TABLE tablename;

For example:

TRUNCATE TABLE customers;

This will delete all data from the customers table.

Image of TRUNCATE TABLE Statement

9. JOIN Statement

The JOIN statement is used to combine data from two or more tables based on a related column. The basic syntax is:

SELECT column1, column2,...
FROM table1
JOIN table2
ON table1.column = table2.column;

For example:

SELECT customers.name, orders.order_date
FROM customers
JOIN orders
ON customers.id = orders.customer_id;

This will retrieve the name column from the customers table and the order_date column from the orders table where the id column in customers matches the customer_id column in orders.

Image of JOIN Statement

10. INDEX Statement

The INDEX statement is used to create an index on a column or set of columns in a table to improve query performance. The basic syntax is:

CREATE INDEX indexname
ON tablename (column1, column2,...);

For example:

CREATE INDEX idx_name
ON customers (name);

This will create an index named idx_name on the name column in the customers table.

Image of INDEX Statement

We hope this cheat sheet of essential SQL commands has been helpful! Whether you're a seasoned database administrator or just starting out, these commands will help you perform common tasks and troubleshoot issues in your database.

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