A database language is made up of two languages: Data Definition Language (DDL) and Data Manipulation Language (DML). DDL (Data Definition Language) is used to specify the database schema database structure, which is the primary distinction between DDL and DML.
On the other hand, data from the database can be accessed, altered, or retrieved using DML (Data Manipulation Language). Let’s use the comparison table below to talk about the differences between DDL and DML.
DDL Definition (Data Definition Language)
Data Definition Language is what it stands for. The database structure, or database schema, is defined by the Data Definition Language. Additional characteristics of the data defined in the database are also defined by DDL, including the domain of the attributes. The Data Definition Language also offers the option to specify some restrictions that would preserve the consistency of the data.
Let’s talk about some DDL commands:
- A new database or table can be created using the CREATE command.
- The content of the table can be changed using the ALTER command.
- DROP is used to remove specific items from a table or database.
- The table’s entire contents can be deleted using TRUNCATE.
- The database’s content can be renamed using RENAME.
It is clear that DDL only defines the table’s columns (or attributes). DDL accepts commands and produces output that is stored in the data dictionary, just like other programming languages (metadata).
DML (Data Manipulation Language) definition
Data Manipulation Language is what it stands for. The Data Manipulation Language is used to populate or fill the schema (table) that was created by DDL (Data Definition Language). Each row in the table is referred to as a “tuple” and is filled using DDL. You can insert, modify, delete, and retrieve data from the table using DML.
There are two types of DML: declarative and procedural. Procedural DMLs describe where to retrieve data and how to retrieve it. Declarative DMLs, on the other hand, merely specify what data should be retrieved. It doesn’t explain how to obtain that information. Declarative DMLs are simpler because all the user needs to do is specify the data that is needed.
The following are the DML commands:
- To retrieve the data from the table, use SELECT.
- When pushing data into the table, INSERT is used.
- The data in the table was reorganized using UPDATE.
- The DELETE command is used to remove data from a table.
When it comes to SQL, declarative DML, which is non-procedural, is used for DML.
The DML and DDL
The main variations between DDL and DML are:
- The acronym for DDL is Data Definition Language.
- The only purpose of DDL instructions is to define the database table structure.
- The approach is declarative.
- They are not followed by the WHERE clause.
- Database objects cannot be changed.
- It is not further classified.
- DCL commands such as the ROLLBACK command are inapplicable in this situation.
- The entire database or table is updated when changes are made.
- The fundamental DDL commands are CREATE, DROP, TRUNCATE, RENAME, etc.
- Data Manipulation Language is referred to as DML.
- DML statements are used to update or change the base table.
- It is a necessary technique.
- The WHERE clause comes after DML commands.
- The database schema is divided into procedural DML and non-procedural DML, and it cannot be changed.
- The rollback command allows changes to be undone.
- Changes to only one or more records can be affected by changes.
- The fundamental DML commands are UPDATE, INSERT, MERGE, DELETE, etc.
To put it simply, DDL commands define the structure of tables while DML commands modify the data in the tables. Users can interact with the database more easily using either language.
Both DDL and DML are required to build a database language since they both need to create and access the database.