Explore SQL Commands: Top 25 Commands

SQL Commands – Administration or development in relational databases is based on structured query language (SQL). Structured Query Language provides a set of commands that let users/DBAs,/Developers work with databases efficiently. DDL, DML, DCL, DQL, and TCL are the five main categories into which these instructions fall. Database administrators, developers, and users involved in data management must know these commands deeply to perform their tasks.

📝 Introduction to SQL Commands

The SQL commands are instructions to communicate with a database to perform tasks, functions, stored procedures, and queries. These commands are essential for storing data for future reference, manipulating data, managing database structures, controlling user permissions and access, and handling transactions properly.

🕰️ A Glimpse into History

The SQL was developed in the 1970s by IBM scientists Donald D. Chamberlin and Raymond F. Boyce. It was initially called SEQUEL (Structured English Query Language) and thereafter shortened to SQL only. With the addition of several features and extensions, such as Transact Structured Query Language or T-SQL (Microsoft SQL Server) and PL/SQL (Oracle), to expand its functionality, SQL has evolved into the industry standard for RDBMS (relational database management systems).

❓ What are the SQL Commands?

SQL commands are standardized instructions used to perform specific operations on a database. They allow users to create a table, update row(s), retrieve required data, delete a particular row or column, store data in a table, and manage it. The primary categories include:

Data Definition Language (DDL):

DDL commands define and modify the structure of database objects.
They create, alter, and drop tables, indexes, and schemas.
Examples include CREATE, ALTER, DROP, and TRUNCATE.
These commands affect the schema and are auto-committed.
DDL operations are essential for setting up and organizing the database framework.

Data Manipulation Language (DML):

DML commands handle data manipulation within existing tables.
They allow for inserting, updating, and deleting records.
Standard DML commands are INSERT, UPDATE, and DELETE.
These operations can be rolled back if enclosed within transactions.
DML is crucial for maintaining and modifying the data stored in the database.

Data Control Language (DCL):

DCL commands manage access rights and permissions for users.
They control who can perform certain operations on the database.
Key DCL commands include GRANT and REVOKE.
These commands ensure data security and proper access control.
DCL is vital for enforcing database security policies.

Data Query Language (DQL):

DQL queries and retrieves data from the database.
The primary DQL command is SELECT.
It helps users to fetch the required data from the database on specific criteria.
DQL is essential for data analysis and reporting.
It enables users to view and interpret the stored information.

Transaction Control Language (TCL):

TCL commands manage transactions within the database.
They ensure data integrity by controlling the execution of DML operations.
Standard TCL commands are COMMIT, ROLLBACK, and SAVEPOINT.
These commands help maintain consistent and reliable data states.
TCL is crucial for handling complex operations that require multiple steps.

Advantages of SQL Commands:

It Provides Uniformity: SQL is an ANSI and ISO standard, ensuring platform consistency.

Adaptability: It supports simple as well as complex queries for data manipulation.

Integration with languages and platforms: We can easily integrate with various programming languages and platforms.

User-Friendly: SQL has English-like syntax, making it easier and more accessible to non-programmers.

Disadvantages of SQL Commands:

A Bit of Complexity: Advanced queries can become complex and challenging to manage.

Limited Procedural Capabilities: Standard SQL lacks procedural features, requiring extensions.

Performance Issues: Poorly written queries can lead to performance bottlenecks.

🐞 Common Issues with DDL, DML, DCL, DQL & TCL

DDL: Accidental data loss due to DROP or TRUNCATE commands.

DML: Unintended data modifications without proper WHERE clauses.

DCL: Over-permissioning users leads to security risks.

DQL: Performance issues due to unoptimized queries.

TCL: Data inconsistencies are caused by improper transaction handling.

Conclusion

DDL, DML, DCL, DQL, and TCL are categories of SQL commands that are used for efficient database administration as well as development. Knowing each kind of SQL command improves our database skills, from using DDL commands to create and change tables to using TCL instructions to manage transactions. SQL provides a wide range of features & capabilities for both maintaining the database and altering data. Thanks to this, we hope you now have a thorough understanding of SQL commands, their categories, syntax, and examples.