What is the Difference Between DDL and DML? with Proper Definition and Brief Explanation

The main difference between DDL and DML is that DDL helps to change the structure of the database while DML helps to manage the data in the database.

A database is a collection of related data. DBMS (Database Management System) is a software that helps to access and manage databases easily. They allow multiple users to access data and provide data security. The relational DBMS stores data in table format. A table consists of rows and columns. The rows represent each record, while the DML columns represent attributes. SQL (Structured Query Language) is the language for storing, managing, and retrieving data in relational databases. The user can perform various operations on the database using SQL commands. Two types of SQL commands are DDL and DML.

Key Areas Covered

1. What is DDL?
     – Definition, Functionality
2. What is DML?
     – Definition, Functionality
3. What is the difference between DDL and DML?
     – Comparison of key differences

Key terms

DBMS, DDL, DML, SQL

What is DDL?

DDL stands for Data Definition Language . DDL commands help create the database structure and the other database objects. Your commands are auto-committed. Therefore, the changes are saved in the database permanently.

Some DDL commands include create, drop, and alter. The create command helps create new databases and tables. The drop command helps drop databases and tables, while the alter command helps modify an existing database object, such as a table. Those are some common DDL commands.

What is DML?

DML stands for Data Manipulation Language . DML commands help manage the data stored in the database. However, DML commands are not autocommits. Therefore, the changes are not permanent. Therefore, it is possible to reverse the operation.

Some DML commands include insert, update, delete, and select. The Insert command helps to store new records or rows in the table while the Update command helps to modify an existing record in the table. Meanwhile, the delete command allows you to delete a certain record or a set of records from the table, while the select command allows you to retrieve specific records from one or more tables.

                                                           Figure 1: SQL Commands

Besides DDL and DML, there is another type of command like DCL. DCL allows you to control the users who can access the databases. Grant and revoke are two DCL commands. Grant grants privileges to a user, while revoking takes back the privilege granted by the user.

Difference Between DDL and DML

Definition

DDL is a type of SQL command that helps define database schemas. In contrast, DML is a type of SQL command that helps retrieve and manage data in relational databases. These definitions explain the main difference between them.

Long Way

DDL stands for data definition language while DML stands for data manipulation language.

Commands

Create, drop, alter some DDL commands while inserting, updating, deleting and selecting some DML commands.

Effect

Another difference between DDL and DML is that DDL commands affect the entire database or table, but DML commands affect one or more records in a table.

Commit

SQL statements with DDL commands cannot be reversed. On the other hand, SQL statements with DML commands can be reversed. Thus, this adds up to another difference between them.

Conclusion

SQL is the language that helps to perform various operations on data in relational databases. DDL and DML are two types of SQL commands. The main difference between them is that DDL helps to change the database structure while DML helps to manage the data in the database.

Reference:

1. “SQL Overview.” Www.tutorialspoint.com, available here.
2. “Introduction to SQL”. Introduction to SQL (Structured Query Language) | Studytonight, available here.

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