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September 7, 2021

Structured Query Language (SQL) Explained – What is SQL?

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In the process of learning about databases or exploring new programming languages, you will probably come across the term “SQL”. Experienced developers will likely already know what SQL is and are likely to have used it extensively in their database projects. Beginners who are just embarking on their programming journey and would like to know more about building, managing, and retrieving information from databases will benefit from this guide. If you are a novice and are curious to find the answer to “what is SQL?” then this article is for you!

So, what is SQL? The acronym stands for “Structured Query Language”. A query language is a programming language designed to retrieve specific information from databases. It’s one thing to be able to input a bunch of data and build a database. However, we need a systematic way to ask for specific data back—to get exactly what we need when we need it—from said database. Otherwise, it’s pointless to store data that is unsortable, unmanageable, unretrievable, or functionally useless. SQL facilitates this process, and it’s called “querying”. 

What is SQL used for? Most companies today already store their data in large databases. There is a wide range of database types, but chances are most of them can be queried by SQL. Understanding SQL will help you grasp and work seamlessly with the vast world of relational databases. If you want to get a job in data or work with company databases or spreadsheets, you will benefit from mastering SQL. 

You will also be interested to learn that there is more than one way to keep a database. You can create a centralized or decentralized one. For decentralized database applications on dApps, blockchain, and Web3, it helps to know that next-gen tools such as Moralis can supercharge the development of such cutting-edge projects.  

What is SQL – The Basics

SQL, or Structured Query Language, is pronounced as the letters S-Q-L or, alternatively, “sequel”. It’s the language that we use to interact with information stored in a relational or SQL-type database. You can also define it as the standard language for relational database management systems (RDBMSs). 

Any action that we need to take on a database or the information stored in it can be achieved with the SQL syntax. Using SQL, you can create or change the structure of a database or a table. SQL can also help you store, manipulate or retrieve data from tables or databases. 

SQL is an ISO (International Organization of Standardization) language and is in high demand in various industries. Those interested in going into blockchain development will be glad to know that it ranks among the most popular languages used in the blockchain industry and is supported by blockchain-based projects alongside Solidity, C and C++, JavaScript, Ruby, Python, and Go. 

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What is SQL: The History of SQL

In 1973, IBM began working on a relational database language based on a relational model paper published in 1970 by Edgar F. Codd, now known as the “father of relational databases”. The new language was an upgrade to their earlier non-relational methods of storing and retrieving data, called “ISAM” and “VSAM”. While the basic operations like storage, deletion, and retrieval could be performed, they could only be done on one record at a time. Eventually, the new language that emerged was named “SEQUEL”, later abbreviated and turned into SQL. Oracle released SQL’s first commercial version in 1979, which they based on the original IBM version.

What is SQL: A Non-Procedural Language

To understand what SQL is and discover its use cases, we need to dig deeper into how the programming language works. 

SQL is a non-procedural or declarative query language. While a procedural language requires you to specify what to do and how to do it using a sequence of instructions or a step-by-step procedure, a non-procedural language simply asks you to specify the “what to do” part and doesn’t need you to specify the “how to do it” part. 

Procedural languages are command-driven and work through the state of the machine. Non-procedural ones like SQL are function-driven and work through mathematical functions. Unlike procedural languages, the semantics of non-procedural languages is quite simple and can return any value or datatype. Both types use recursive calls, but procedural languages use iterative loops on top of recursive calls. They also have large program sizes. On the other hand, non-procedural languages have a small program size and are better suited to time-critical applications. 

Examples of procedural languages are Fortran, COBOL, ALGOL, BASIC, C, and Pascal. The list of non-procedural languages includes Prolog, Lisp, and of course, SQL.

What is SQL: Relational Databases

In addition to the above-stated information, you need a foundational understanding of relational databases. That way, you’ll be able to answer “what is SQL?” and “what is SQL used for?” more thoroughly.

A relational database is a kind of database that stores related information across multiple tables. It allows you to query or ask for information simultaneously from more than one table.

To illustrate this, think about a business wanting to track its sales or customer information. In the beginning, an Excel spreadsheet can seem like a practical idea. Such data can be separated into columns, segregating information such as the date of the order placement, the order number, the customer’s name, their address and other contact information, the amount due, etc. As you build your customer base and expand your business, such a basic database will prove to become bulky, unmanageable, and redundant. You will encounter problems with repeat orders, repeated data entries which cause unnecessary redundancy and take up more space than warranted. Overall, the system becomes more inefficient as it builds. 

Basic data entry systems also encounter problems with data integrity. You can’t be sure that every single entry field is given the correct data type or whether there is uniformity in the system of entry. 

SQL and relational databases were introduced to solve the above problems and take databases to a new level of manageability.

What is SQL Used For?

SQL is used by millions of developers across the world for many great reasons. It offers many capabilities, including the following:

  • It lets users access, define, manipulate, and manage the data in RMDBSs, as described previously.
  • It lets users create and drop tables and databases, as well as set permissions on tables, views, and procedures.
  • Within a database, users can create various functions, including view and stored procedure functions. 
  • It lets users embed data within other languages through the use of SQL modules, pre-compilers, and libraries.

What is SQL: Advantages

Aside from learning what SQL is used for, SQL’s importance in a programmer’s skill set goes beyond simple functions and can be summarized as follows:

  • It’s easy to master. As a query language rather than a programming language, you can grasp it more easily because its syntax is similar to logical English sentences.
  • It offers you a better understanding of your dataset(s). 
  • Being an ISO standard language, it doesn’t change much. Once you’ve mastered SQL, you don’t have to worry about too many updates, and you can be assured of a skill you can apply for a long time.
  • Much better than Excel. With SQL, you are capable of handling much larger (even massive) datasets compared to regular spreadsheets.

What is SQL – Commands and Sub-Languages

To give you an idea of what SQL is and how this language is used, you need to understand the basic SQL commands. The most basic of these that are required to interact with relational databases include “CREATE”, “SELECT”, “INSERT”, “UPDATE”, “DROP”, and “DELETE”. However, there are more commands, as you will see below.

To perform all its functions, SQL classifies its commands into several sub-languages according to their purpose and nature. 

DDL – Data Definition Language

This classification includes “CREATE”, “ALTER”, and “DROP”. Such commands allow programmers to create and modify or alter database objects, including tables. 

  • CREATE – Starts a new table, view of a table, or another object in your database.
  • ALTER – Changes a current object in the database.
  • DROP – Removes or deletes a view of a table, an entire table, or objects in the database.

DML – Data Manipulation Language

The commands under this classification are used in the storage and modification of data in a database. 

  • SELECT – Retrieves records from one or several tables.
  • INSERT – Creates a record within the database.
  • UPDATE – Modify records.
  • DELETE – Erase records.

DCL – Data Control Language

The DCL sub-language is used when you want to set controls on the access of your database. 

  • GRANT – Gives a user access privilege.
  • REVOKE – Removes a granted privilege.

TCL – Transaction Control Language 

This classification lets you handle modifications done by DML commands. 

  • COMMIT – Ends a current transaction and allows you to establish any changes made during such a transaction as permanent.
  • ROLLBACK – Is the antithesis to “COMMIT”. It lets you end a transaction, but it will undo any changes that happened during that transaction. 

With an idea of these basic sub-classifications and commands, you now have the answer to “what is SQL?”. You also have a better understanding of SQL and the extent of what it can be used for. 

What is SQL: Next Steps

This article is designed to introduce the basic principles of SQL and enable you to answer questions such as “what is SQL?” and “what is SQL used for?”. Treat it as a springboard to direct you to more complex learning materials on the way to your mastery of databases. With this basic knowledge, you can start practicing by building your first database and downloading the necessary software, the most popular of which is “MySQL”. After downloading it, you can proceed with mastering these basic commands. 

You can learn further by following more in-depth online tutorials with practical examples. Don’t forget to get involved in the community and find friends or mentors to simplify your learning process. With enough diligence and practice, you’ll be proficient in SQL in no time!

Blockchain or Relational Databases?

For decades, we have been accustomed to storing data in a centralized manner. Large multinational companies control massive amounts of the world’s data, giving them a significant business advantage. With blockchain, developers are shifting data towards decentralization. They are challenging the idea of centralized databases or at least offering a new viable alternative to the traditional model. 

Through blockchain technology, data storage is becoming decentralized and disintermediated, with multiple copies of databases stored on different computers worldwide. We are no longer tied to the non-transparent, monolithic culture around Web2 databases. Blockchain and Web3 are providing us with new options and revolutionizing the way our data is being stored, hosted, managed, and accessed. 

Should we prefer blockchains to traditional databases, then? Not necessarily. You need to tailor your choice of infrastructure to your purpose, resources, capabilities, and preferences. Blockchains offer a robust, decentralized, and fault-tolerant way of storing and accessing data. However, relational databases have performance advantages, not to mention a distinct edge in their ease of deployment, as they don’t require the node and backend infrastructure needed to run Ethereum and other blockchains. 

You also need to consider the overlaps between these technologies. Smart contracts exist as “stored procedures” on relational databases, and both types of databases can be used together in hybrid projects. 

Choosing Your Ideal Database

If you’re working on a private enterprise project, you need to evaluate your options carefully. If it doesn’t benefit from openly available data and disintermediation, and your client base is relatively small and steady, you should consider using a relational SQL database.

However, if you’re planning on building a decentralized app on Ethereum, Polygon, Binance Smart Chain (BSC), or Arbitrum with an ecosystem involving the use and creation of tokens, then you would benefit from storing your data on a multi-layered blockchain structure. It would help if you also evaluated whether disintermediation is a crucial feature in your build.

While relational databases edge out blockchains on performance, blockchains provide a robust, massively parallel data infrastructure. To get started on your blockchain-based infrastructure, you need to run a node and gain access to a multitude of next-gen Web3 tools that support your blockchain’s backend. As such, make sure to check out Moralis Speedy Nodes. Moralis Speedy Nodes eliminate the tedious steps of spinning up your node from scratch and provide a way to access Web3 blockchain data and integrate them into your dApp development using Moralis query.

SQL in Blockchain Development

As previously discussed, blockchain and relational databases offer specific advantages. That is in theory. In practice, the choice is often not black and white. Because blockchains have no querying abilities, one must consider the most feasible route: to add blockchain features to a traditional database. As the network grows and adds more nodes, the network traffic can multiply many times without an equivalent adjustment of throughput, capacity, or latency. This can give rise to all sorts of issues. As a solution to this, you can create a multi-layered infrastructure where the data is transacted using a computer interface or database interface and supported by blockchains. Projects that employ a traditional interface over blockchain framework include Cassandra, ChainifyDB, CovenantSQL, Postchain, BigChainDB, Modex BCDB, and others. 

Aergo is another interesting example of this hybrid-layered approach. It uses SQL smart contracts to create a platform that lets enterprises write and execute smart contracts within commercial environments. 

What is Moralis Query?

Now that you understand what SQL is and the importance of queries, you might want to learn more about how they relate to blockchain builds. If you choose to develop your Web3 app on Moralis, you take the most convenient route to develop your blockchain project through serverless computing. Furthermore, you eliminate the numerous difficult steps and costs associated with handling a blockchain-based database and setting up your physical server. Moralis, apart from giving you a way to set up a node quickly, helps you define, manage and retrieve data and integrate it into your dApp development or any other blockchain project.

Moralis query is Moralis’ user-friendly language of querying data from a Moralis server that allows a seamless dApp development process without the need to purchase a server of your own. To have an idea of how it works, check the first of a four-part video here:

From the video above, you’ll gain insight into the extensive support Moralis provides for Web3 and dApps. Moralis helps you bypass all the burdensome or monotonous backend infrastructure setup and other time-consuming steps. Why use Moralis? It’s the ultimate Web3 development platform that helps you focus on creating an astonishing frontend so you can launch your dApp as swiftly as possible! 

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