Types of Database Languages

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A database language is a computer language used to manipulate and query data in a database. It consists of a set of commands, syntax, and keywords used to perform specific tasks. There are different database languages, each designed for a particular purpose.

I’ll explore types of database languages and what sets them apart. Let’s get started!

Data Manipulation Language (DML)

Data Manipulation Language (DML) lets users and administrators interact with database data using commands. Its primary goal is to make it easy and efficient to insert, update, delete, or query data.

The commands of DML is as follows:

  • SELECT: It is used to extract data from a database. You can use the SELECT statement to return all or part of the data in a table.
  • INSERT: You can use this command to add new data to a table.
  • UPDATE: With the update command, you can update existing data in a table.
  • DELETE: This command is used to delete or remove data from a table.

Data Manipulation Language (DML) falls into two categories: Procedural DML and Non-procedural DML.

Procedural DML

In procedural data manipulation, you define what data you need and how to retrieve it. This method requires a good grasp of the data and their relationships. The main benefit is that procedural DML is easier to grasp and apply.

Non-procedural DML

In non-procedural data manipulation, the user specifies what data is needed, not how to get it. Non-procedural DML is more flexible and easier to use than procedural DML. The main drawback of non-procedural DML is that it requires a detailed understanding of the database structure.

Data Definition Language (DDL)

Database administrators use Data Definition Language (DDL) to shape and manage database structures. This involves defining tables, columns, and relationships. DDL also helps create and handle indexes and views. You can even alter the database structure, like adding or dropping data.

The key commands of Data Definition Language are:

  • CREATE: The command is used to create a table, index, or view.
  • DROP: Drop command is used to delete an object from the database.
  • ALTER: It is used to change the properties of an existing object in the database.
  • TRUNCATE: The command deletes all data from a table while preserving the table structure.

Transaction Control Language (TCL)

Transaction Control Language (TCL) manages database transactions. A transaction is a set of SQL commands executed as one unit. The tasks must be completed for the transaction to succeed.

Commands of TCL are as follows:

  • COMMIT: This command saves all the changes made by the transaction.
  • ROLLBACK: This command is used to undo all the changes made by the transaction.
  • SAVEPOINT: This command is used to create a savepoint, which is a marker that is used to identify a specific point in a transaction.
  • SET TRANSACTION: This command is used to set the characteristics of a transaction.

Data Control Language (DCL)

Data Control Language (DCL) is a database language that controls user access to data. It doesn’t change the data but sets permissions on who can handle it. Think of it as a security guard for your information. Using DCL, administrators can grant or revoke user privileges.

Some of the DCL commands are as follows:

  • GRANT: It is used to give a user access privileges to the database.
  • REVOKE: It can take away a user’s access privileges to the database.
  • LOCK TABLE: Used to lock a database table so that only one user can access it at a time.
  • UNLOCK TABLE: As the name suggests, it can unlock a database table.

Most Popular Database Languages

Here are some of the most popular and widely used database languages:

XQuery

XQuery is a language for querying XML data. It can query XML and relational data, making it popular in enterprises. Use XQuery to query databases that store XML data, like eXist or MarkLogic.

SQL

SQL (Structured Query Language) is the most popular database language. Used with databases like MySQL, Oracle, Microsoft SQL Server, and PostgreSQL, you can create, read, update, and delete data within a relational database using SQL.

NoSQL

NoSQL offers a powerful alternative to SQL, perfect for handling unstructured and semi-structured data. Popular options include MongoDB, Cassandra, and NeoJSON.

OQL

OQL (Object Query Language) is a database language used to query object-oriented databases. It’s the native language of Objectivity/DB, a popular object-oriented database system.

PL/SQL

PL/SQL is a procedural extension of SQL used in Oracle databases. It includes features like loops, conditional statements, and exception handling.

Which Database Language Should You Learn?

Choosing the right database language depends on your data type. To query XML data, learn XQuery. For relational data, use SQL. For object-oriented data, go with OQL.

You don’t need to learn every database language. If you know one, you can query different types of data. For instance, with SQL, you can use XML functions to query XML data.