If you are a beginner or intermediate then this article gives you a good overview of SQL and if you are an expert then it may help you to get something new on the same or help to refresh your knowledge. Well, in this article post, you will learn all about SQL full form, the type of languages and its extensions, the history of SQL and its restrictions, how it works, why we learn SQL, its keywords, and syntaxes, common uses of SQL in DBMS along with the SQL injections.
Introduction to SQL
The initial version of SQL was called SEQUEL (Structured English Query Language). The earlier version of SEQUEL was designed by an IBM research center in 1974 and 1975 that’s why the copyright of SQL or SEQUEL is under IBM. Now SQL is a domain-specific language used in programming and designed to manage and communicate with data in RDBMS to store, manipulate and retrieve. As per American National Standards Institute (ANSI), SQL is the standard language for RDBMS.
What is SQL Full Form?
Guys, SQL full form is Structured Query Language which is a computer database language. SQL is used to manage and manipulate relational databases. Now SQL is a domain-specific language used in programming and designed to manage and communicate with data in relational database management systems (RDBMS).
Type of Languages
There are two types of languages –
- How to Do? (Procedural) examples are – C, C++, .NET, JAVA, PHP, etc. front end development programming languages.
- What to Do? (Non-Procedural) examples are – OS Commands and RDBMS like MS Access, Oracle, Informix, IBM DB2, Sybase, Microsoft SQL Server, MySQL, PostgreSQL, etc back end database programming languages.
Extensions of SQL
Now, these days SQL is used by most RDBMS and most of them use their proprietary extensions on their system. Given below few extensions of Jet-SQL, T-SQL, and PL-SQL along with the extension SQL full form –
Jet-SQL, T-SQL, and PL-SQL Full Form
Below are the extension of Jet-SQL, T-SQL, and PL-SQL as well as extension SQL full forms –
- Jet-SQL: The extension used in Microsoft Access is called Jet-SQL. Jet-SQL full form is Joint Engine Technology in Structured Query Language.
- T-SQL: The extension used in Microsoft SQL Server is called T-SQL. T-SQL full form is Transact – Structured Query Language.
- PL-SQL: The extension used in Oracle is called PL-SQL. PL-SQL full is Procedural Language in Structured Query Language.
Restrictions in SQL
There are mainly three types of restrictions in SQL-
- Single-line query execution
- Coding or programming is not allowed
- Exceptions are not handled
History of SQL
There is a summary of SQL history that in the year 1970 a relational model for databases was given by Dr. Edgar Frank “Ted” Codd and then in the year 1974 SQL (Structured Query Language) came into the picture of the world. IBM started working development of Dr. E. F. Codd’s idea and released a product named System R in the year 1978. IBM invented and described the relational model database first time so it’s known as the father of relational databases. In the year 1986, IBM released the prototype of a relational database model as per the standard of ANSI (American National Standards Institute) which was known as Oracle in later years. IBM launched their first version of SQL RDBMS in 1989 and after that continuously upgraded the versions of RDBMS which we are using now.
How SQL Works?
SQL communicates with a database and relational databases by using its specific commands which are known as SQL statements. SQL statements help to perform various database operations like inserting, updating, and retrieving data in a database. Every relational database management system (RDBMS) are using SQL statements like Microsoft SQL Server, Oracle, MySQL, PostgreSQL, etc.
Why Do We Learn SQL?
Nowadays, SQL (Structured Query Language) is a very popular and leading query language used in all kinds of applications to interact with any relational database management system like MS Access, MySQL, SQL Server, Oracle, PostgreSQL, and NoSQL, etc. Most government agencies, NGOs, Banks, IT companies, and various businesses are using SQL to manage and analyze data on a large scale. It uses its queries and statements with common English commands to create, modify and delete the database objects and is also very easy to learn.
SQL queries and syntaxes are almost similar to use in different RDBMS even different proprietary syntaxes of a few RDBMS. SQL helps to create, drop and set the permissions on stored procedures, functions, triggers, views, databases, and tables. Users can access the data, describe the data and manipulate the data from any RDBMS. SQL helps users to analyze complex data as well as huge reporting tasks in an effective and efficient manner.
Applications of SQL
SQL is basically used by businesses that have and operates huge amount of data. It helps organizations store and manage their data in an organized, effective, and efficient manner to retrieve and analyze as per their need. SQL is used by approximately all varieties of applications and organizations as follows –
- Banking and Finance
- Business and IT Companies
- Retail and e-commerce
- Telecommunications
- Government
- Education
SQL Keywords and Syntaxes
There are specific keywords and syntaxes to write SQL statements. It is very important to understand how each syntax and keyword works before writing the SQL statements. You will be able to become more proficient in writing and executing SQL statements with time and practice. Refer below some basic syntax of SQL –
Syntax:
SELECT TOP FROM WHERE JOIN GROUP BY HAVING ORDER BY
SQL Statements (Commands)
5 SQL statements (Commands) are being used in SQL queries –
- DDL (Data Definition Language) – i.e., CREATE, ALTER, DROP, TRUNCATE
- DML (Data Manipulation Language) – i.e., INSERT, UPDATE, DELETE, SELECT (Strictly a part of DQL Command)
- DCL (Data Control Language) – i.e., GRANT, REVOKE, DENY
- TCL (Transaction Control Language) – i.e., BEGIN, COMMIT, ROLLBACK, SAVEPOINT
- DQL (Data Query Language) – i.e., SELECT
Structure: Below structure for reference –
1. DDL (Data Definition Language) Commands
The DDL is an abbreviation of Data Definition Language. It is used to create and modify the structure of database objects in a database, such as the creation or the deletion of a table, Index, and Views.
Example: CREATE, ALTER, DROP, and TRUNCATE statements
a) CREATE Command: A user can create a new database, table, views, etc using create command
b) ALTER Command: A user can modify existing database objects and tables etc using alter command
c) DROP Command: A user can delete an existing database, table, views, etc permanently using the drop command
d) TRUNCATE Command: A user can delete entire table data including resetting its identity column permanently using the truncate command
2. DML (Data Manipulation Language) Commands
The DML is an abbreviation of Data Manipulation Language. It is used to retrieve, store, modify, and delete data in a database.
Example: INSERT, UPDATE, DELETE, and SELECT (Strictly a part of DQL Command) statements
a) INSERT Command: A user can insert new records into a table using the insert command
b) UPDATE Command: A user can change, or update any data in the existing table using the update command
c) DELETE Command: A user can delete or remove any data in the existing table using the delete command
d) SELECT Command: A user can insert new records into a table using the select command as well. The ‘SELECT’ statement is strictly a part of DQL (Data Query Language) commands not DML. Although SELECT is considered to be a part of DML command in common practice. Thus all the SQL data statements consist of a DML command.
3. DCL (Data Control Language) Commands
The DCL is an abbreviation of Data Control Language. Data control language command is used to create roles, permissions, and referential integrity as well, as to control access to a database to secure.
Example: GRANT, REVOKE, and DENY statements
a) GRANT Command: A DBA can allow or provide specific or full access permissions to a specific user using a grant command
b) REVOKE Command: A DBA can disallow or remove specific or full access permissions to a specific user using the revoke command
c) DENY Command: A user can stop or deny specific permissions to a specified user or group in the database even if the user has a certain list of privileges
4. TCL (Transaction Control Language) Commands
The TCL is an abbreviation of Transaction Control Language. Transaction control language command is used to manage different transactions occurring within a database.
Example: BEGIN, COMMIT, ROLLBACK, and SAVEPOINT statements
a) BEGIN Command: A user can control any upcoming changes in the database while executing any DML or transaction queries to commit or roll back using the BEGIN command. This is important to run ‘BEGIN’ before the execution of any DML scripts so that the commit and rollback commands can be performed
b) COMMIT Command: A user can apply a permanent change to the database while any DML query or transaction performed using the commit command but it will work only when the START TRANSACTION command is executed before DML or transaction query is executed
c) ROLLBACK Command: A user can undo a previous change applied to the database while any DML query or transaction performed using the rollback command but it will work only when the START TRANSACTION command is executed before DML or transaction query is executed
d) SAVEPOINT Command: A user can roll back the transaction back to a certain point using the savepoint command. This command works only when a savepoint is created in any SQL transactional query
5. DQL (Data Query Language) Commands
The DQL is an abbreviation of Data Query Language which is used to retrieve data only from a database table
Example: SELECT statement
SQL Processing Query
SQL engine determines the best way to process a user’s query request and figure out how to perform the task when a user executes an SQL query or command at any RDBMS system. Below are the basic components of the SQL query process –
SQL Query Engine
SQL Query Optimization Engine
Classic SQL Query Engine
SQL Query Dispatcher
SQL Query Process Chart
Below SQL query process chart for reference –
Common uses of SQL
SQL is commonly used to store, manipulate, and delete data from a database along with a variety of different scenarios as follows –
- Data Origination
- Data management and organization
- Data Retrieval and analysis
- Report generation
- Data Manipulation and maintenance
What is SQL injection?
SQL injection corrupts, retrieves, or modifies data in an SQL database using SQL queries. This is a cyberattack that involves tricking the database through SQL Injection. Nowadays hackers are using SQL injections to update, corrupt, or fetch data from the database. Attackers might write a SQL query without any user or person name in a submission form or link to perform a SQL injection attack.
Difference between SQL and NoSQL
While SQL is a very popular language for managing relational databases, there is also another type of database language known as NoSQL. NoSQL databases are designed to handle unstructured and semi-structured data, and they use a non-relational data model. While NoSQL databases are useful in certain situations, such as for big data applications, SQL is still the preferred language for most organizations due to its scalability, efficiency, and flexibility.
Best Practices to Write SQL Queries
It is most important to follow best practices while writing SQL queries to ensure that the queries are efficient, secure, and easy to understand. Here are some best practices for writing SQL queries as follows-
- Use of consistent formatting- Consistency in formatting makes the code easy to read and understand.
- Use of comments- Comments can be used to explain what the code is doing and why.
- Use of aliases- Aliases can make the code easier to read, especially when working with multiple tables.
- Avoid using SELECT *- Using SELECT * can be inefficient, as it retrieves all columns in a table. Instead, specify the columns that are needed.
- Use of indexes- Indexes can improve query performance by allowing the database to quickly find the data that is needed.
How to Learn SQL?
Learning SQL is a valuable skill for anyone working with data. There are several resources available for learning SQL, including online courses, books, and tutorials. Some popular SQL courses include Udemy, Codecademy, and Coursera. There are also many SQL forums and communities where users can ask questions and get help with SQL-related issues. SQLPOST academy also tries to cover the entire SQL by providing best practices to understand easily with live practical screenshots.
FAQs
Refer to the full forms as follows –
SQL: Structured Query Language, Jet-SQL: Joint Engine Technology in Structured Query Language, T-SQL: Transact – Structured Query Language, PL-SQL: Procedural Language in Structured Query Language, DDL: Data Definition Language, DML: Data Manipulation Language, DCL: Data Control Language, TCL: Transaction Control Language, and DQL: Data Query Language.
SQL (Structured Query Language) is a medium of communication between the database user and the database. It is a standard computer database language and mandatory for a standard RDBMS.
SQL is a standard computer database language used to manage relational databases but MySQL is a specific relational database management system that uses SQL and its standard as per ANSI.
SQL is designed especially for relational database management systems and also it is a standard programming language for RDBMS. So, SQL can be used with relational databases. However, there are many alternative languages that can be used with non-relational databases.
Yes, SQL is easy to learn. It can be easily learned if you have some background in programming.
Conclusion
This tutorial post described basics and advanced knowledge of SQL language and SQL full form. SQL is a standard database language that manages and manipulates the relational database. It is used to perform, data analysis, data mining, and data management tasks. It will provide enough understanding for beginners and professionals. We hope you would have liked this tutorial very well.
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