What are the 5 basic SQL commands?

Certainly! Here are the five basic SQL commands that form the foundation of interacting with relational databases. Understanding these commands is essential for performing essential data operations such as retrieving, adding, modifying, and organizing data.

1. SELECT

Purpose:
The SELECT statement is used to retrieve data from one or more tables in a database. It allows you to specify exactly which columns you want to view and apply various conditions to filter the results.

Syntax:

SELECT column1, column2, ...
FROM table_name
WHERE condition;

Example: Retrieve the first name and email of all employees in the Sales department.

SELECT FirstName, Email
FROM Employees
WHERE Department = 'Sales';

2. INSERT

Purpose:
The INSERT statement adds new records (rows) to a table. It allows you to specify the values for each column in the new record.

Syntax:

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

Example: Add a new employee to the Employees table.

INSERT INTO Employees (EmployeeID, FirstName, LastName, Department, Email)
VALUES (101, 'Jane', 'Doe', 'Marketing', 'jane.doe@example.com');

3. UPDATE

Purpose:
The UPDATE statement modifies existing records in a table. You can update one or more columns and apply conditions to specify which records should be updated.

Syntax:

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

Example: Update the department of an employee with EmployeeID 101 to 'Sales'.

UPDATE Employees
SET Department = 'Sales'
WHERE EmployeeID = 101;

4. DELETE

Purpose:
The DELETE statement removes existing records from a table. You can specify conditions to determine which records should be deleted. Without a WHERE clause, all records in the table will be deleted.

Syntax:

DELETE FROM table_name
WHERE condition;

Example: Delete the employee record with EmployeeID 101.

DELETE FROM Employees
WHERE EmployeeID = 101;

5. CREATE

Purpose:
The CREATE statement is used to create new database objects such as tables, indexes, or views. When creating a table, you define its structure, including column names, data types, and constraints.

Syntax:

CREATE TABLE table_name (
    column1 datatype constraint,
    column2 datatype constraint,
    ...
);

Example: Create a new table named Departments with columns for DepartmentID and DepartmentName.

CREATE TABLE Departments (
    DepartmentID INT PRIMARY KEY,
    DepartmentName VARCHAR(100) NOT NULL
);

Summary of the Five Basic SQL Commands

Tips for Mastering These Commands

1. Practice Regularly:
   Write and execute these commands in different scenarios to become comfortable with their syntax and usage.

2. Understand Constraints:
   Learn about various constraints like PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL, and how they affect data integrity.

3. Use Clauses Effectively:
   Master clauses such as WHERE, ORDER BY, GROUP BY, and HAVING to refine your queries and perform more complex data operations.

4. Explore Advanced Features:
   Once you're comfortable with the basics, delve into more advanced topics like joins, subqueries, indexes, and transactions to enhance your SQL skills.

5. Review and Optimize:
   Always review your queries for efficiency and correctness. Learn how to optimize queries to handle large datasets effectively.

By thoroughly understanding and practicing these five basic SQL commands, you'll build a strong foundation that will enable you to perform a wide range of data operations and excel in SQL-related tasks and interviews.