DDL Full Form

What is the full form of DDL?

Data Definition Language is the full form of DDL. The computer language DDL can be used to create and modify the configuration of database objects within a database. These database objects comprise different components, such as views, tables, indexes, and schemas. Because it chooses the fields and records in the database table, this is sometimes referred to as a "data description language." Let's explore more about DDL.

A data description/definition language: what is it?

Data structures such as tables, indices, and users can be updated using the SQL syntax known as data description language (DDL), also called data definition language. And is employed to specify how a database schema should be described. DDL commands and statements are employed to define data structures, particularly database schemas, in a manner akin to a computer programming language. Examples of DDL commands include create, alter, and drop. When a user accesses a database to view it, they typically do not use these commands. The basic framework of a database structure is formed by these commands, which are used by the database creator.

There are numerous programming languages on the market, some of which are made specifically for modifying databases as well as others for creating them. But in SQL, the DDL language, which covers both operations, is used.

DDL commands with examples

• CREATE TABLE command

It is a command to create a table in a database, as the command's name suggests. The syntax is as follows:

CREATE TABLE table_name (

column1 datatype,

column2 datatype,

column3 datatype,

….

)

For example,

CREATE TABLE employees (

Employee_serial_no INTEGER PRIMARY KEY,

first_name VARCHAR(25) not null,

last_name VARCHAR(25) not null,

address VARCHAR(150) not null,

city VARCHAR(50) not null

);

• DROP Command

The drop command can be used to delete a specific row of data or an entire table.

Syntax:

DROP objecttype objectname.

For Example,

Drop-Table Employee;

Or

Drop-Table Student_List;

• TRUNCATE command

All the data in a table except the table itself can be deleted using the "truncate" command. However, there is a distinction between the DROP table and the TRUNCATE command: with the former, the entire table or structure can be deleted, whereas with the latter, the structure is left intact and only the data within the table is deleted.

Syntax:

TRUNCATE TABLE table_name;

For Example,

TRUNCATE TABLE Student_Data;

Or

TRUNCATE TABLE Employee;

• ALTER Command

The Alter command is used to change a specific table's data. Additionally, it is possible to modify the properties of an object inside a table using the RDBMS (relational database management system). That kind of object is dependent on RDBMS.

Syntax:

ALTER TABLE table_name

ADD column_name datatype;

For example,

ALTER TABLE Student_Data

ADD Roll_No Integer;

Or

ALTER TABLE Employee

DELETE Address;

• COMMENT

Another crucial command for commenting on a data structure is this one. It has three types, single-line commands, multi-line commands, and inline commands, just like any other programming language.

Syntax:

Single Line

— comment_1

— comment_2

SELECT * FROM Students;

Multiple Line

/* Comment_1

Comment_2 */

SELECT * FROM Students;

Inline

SELECT * FROM /* Customers;

For example,

Single Line

–Comment:

SELECT * FROM Students;

Multiline

/* SELECT * FROM Students;

SELECT * FROM Student_Data;

SELECT * FROM Employee; */

SELECT * FROM Business;

Inline

SELECT * FROM Students;

SELECT * FROM /* Student_Data;

SELECT * FROM Employee;

SELECT * FROM */ Business;

• RENAME Command

This command is used to rename a specific table or its contents. ALTER TABLE is another tool that can be used for this.

Syntax:

For renaming a table,

ALTER TABLE table_name

RENAME TO new_table_name;

For example,

Renaming a column

ALTER TABLE Student_Data

RENAME COLUMN roll_number TO serial_number;

3. Conclusion

As a whole, data description language, also known as Data Definition Language, is a subset of SQL (Structured Query Language). A specific set of phrases or commands is employed when building or managing a database. DDL commands include CREATE, ALTER, DROP, RENAME, COMMENT, and TRUNCATE, to name a few. It is utilised by a database creator and functions in the fundamental framework of a database.