Structured Query Language

Owned by Computer Science Department
Aug 01, 2023
2 min read

Structured Query Language (SQL) is a programming language used to manage and manipulate relational databases. Relational databases organize data into tables with rows and columns, where each row represents a record, and each column represents a specific attribute or field of that record.

SQL allows users to interact with databases by defining and executing queries. Queries are statements written in SQL that instruct the database to perform specific actions like retrieving, inserting, updating, or deleting data. Here are some basic SQL operations:

  1. SELECT: This is used to retrieve data from one or more tables. It allows you to specify the columns you want to retrieve and any conditions to filter the results.

Example:

SELECT first_name, last_name FROM employees WHERE department = 'HR';

  1. INSERT: This is used to add new records (rows) to a table.

Example:

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

  1. UPDATE: This is used to modify existing records in a table.

Example:

UPDATE employees SET department = 'Marketing' WHERE employee_id = 101;

  1. DELETE: This is used to remove records from a table.

Example:

  1. CREATE TABLE: This is used to define a new table's structure, specifying the column names, data types, and constraints.

Example:

  1. JOIN: This allows you to combine data from multiple tables based on a related column.

Example:

These are just some of the basic SQL operations. SQL is a powerful language with various other capabilities like aggregations, sorting, filtering, and more. It is widely used in web development, data analysis, and other areas where data is stored in relational databases.