> For the complete documentation index, see [llms.txt](https://serciiit.gitbook.io/introduction-to-software-systems/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://serciiit.gitbook.io/introduction-to-software-systems/databases/sql-curd-operations.md).

# SQL - CURD Operations

 Structured Query Language(SQL) as we all know is the database language by the use of which we can perform certain operations on the existing database and also we can use this language to create a database. CRUD is an acronym that stands for **C**reate, **R**ead, **U**pdate, and **D**elete. These are the four most basic operations that can be performed with most traditional database systems and they are the backbone for interacting with any database.

 **DDL(Data Definition Language) :** DDL or Data Definition Language actually consists of the SQL commands that can be used to define the database schema. It simply deals with descriptions of the database schema and is used to create and modify the structure of database objects in the database. 

* **CREATE** – is used to create the database or its objects (like table, index, function, views, store procedure and triggers).
* **DROP** – is used to delete objects from the database.
* **ALTER** -is used to alter the structure of the database.
* **TRUNCATE**–is used to remove all records from a table, including all spaces allocated for the records are removed.
* **COMMENT** –is used to add comments to the data dictionary.
* **RENAME** –is used to rename an object existing in the database.

 **DML(Data Manipulation Language):** The SQL commands that deals with the manipulation of data present in the database belong to DML or Data Manipulation Language and this includes most of the SQL statements. 

* **INSERT** – is used to insert data into a table.
* **UPDATE** – is used to update existing data within a table.
* **DELETE** – is used to delete records from a database table.

**JOINS -** These are the keywords to join two or more tables based on a condition.

![Various JOINS available offered by SQL](/files/-MbbKqHl-rtKxZOxkeTH)


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