What is SQL?

SQL (Structured Query Language) is a standardized programming language used for managing and manipulating relational databases. It allows you to perform various operations like querying data, updating records, deleting data, and creating or altering database structures.

Basic SQL Syntax

Here are some fundamental SQL commands and their syntax:

1. SELECT
   Used to retrieve data from a database.

   sql
   SELECT column1, column2, ...
   FROM table_name;
   

   Example:

   sql
   SELECT first_name, last_name
   FROM employees;
   

2. WHERE
   Used to filter records.

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

   Example:

   sql
   SELECT first_name, last_name
   FROM employees
   WHERE department = 'Sales';
   

3. INSERT INTO
   Used to insert new records into a table.

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

   Example:

   sql
   INSERT INTO employees (first_name, last_name, department)
   VALUES ('John', 'Doe', 'HR');
   

4. UPDATE
   Used to modify existing records.

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

   Example:

   sql
   UPDATE employees
   SET department = 'Marketing'
   WHERE last_name = 'Doe';
   

5. DELETE
   Used to delete records.

   sql
   DELETE FROM table_name
   WHERE condition;
   

   Example:

   sql
   DELETE FROM employees
   WHERE last_name = 'Doe';
   

6. CREATE TABLE
   Used to create a new table.

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

   Example:

   sql
   CREATE TABLE employees (
       id INT PRIMARY KEY,
       first_name VARCHAR(50),
       last_name VARCHAR(50),
       department VARCHAR(50)
   );
   

7. ALTER TABLE
   Used to modify the structure of an existing table.

   sql
   ALTER TABLE table_name
   ADD column_name datatype;
   

   Example:

   sql
   ALTER TABLE employees
   ADD email VARCHAR(100);
   

8. DROP TABLE
   Used to delete a table and all of its data.

   sql
   DROP TABLE table_name;
   

   Example:

   sql
   DROP TABLE employees;
   

Conclusion

SQL is essential for interacting with relational databases. By mastering these basic commands, you can perform most of the necessary database operations, from creating and managing tables to querying and updating data.