We find almost all the information stored in some type of database on the internet that is easily accessible. A vast majority of data, including personal information, is stored digitally in a server operated by some companies. This data is used and manipulated to make it accessible and convenient, and the medium that is used to do such operations is called SQL.
SQL Full Form
SQL means Structured Query Language, pronounced as “S-Q-L” or sometimes as “See-Quel”. SQL is a standard language for dealing with Relational Databases and can be used to insert, search, update and delete database records. SQL can do lots of other operations too.
Let us know more about SQL:
What is SQL
SQL stands for Structured Query Language. It is the standard and most widely used programming language that lets you access and manipulate databases. It is a domain-specific language that is used to manage and organize data in all sorts of systems in which various data relationships exist.
Brief History of SQL
- It was Invented by Dr. Edgar F. “Ted” Codd in 1970, who described it as a relational model for databases.
- In 1974, the model appeared as Structured Query Language.
- In 1986, IBM developed the prototype of a relational database, which was standardized by ANSI (American National Standards Institute).
- In 1989, the first version of SQL was launched
- In 2003, window functions, XML-related features, etc.were added.
Thereafter several revisions came up to define the functioning of SQL. This included support for XML query language (2006), improved support for temporal databases (2008), data types, isolation levels, logical operators, syntax, etc.
The revision names contain the year when it was made e.g. SQL 2008, SQL 2011, SQL 2016, etc.
SQL is one of the primary Query Languages used for managing relational databases like MySQL Database, Oracle, MS SQL Server, Sybase, etc.
It enables the same database to be run on several computers at the same time. It consists of the following sub-languages for carrying out different operations:
- Data Definition Language (DDL)
- Data Manipulation Language (DML)
- Data Control Language (DCL)
- Transaction Control Language (TCL)
- Data Query Language (DQL)
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An SQL developer must decide what type of data will be stored when creating a table. The data type is a guideline for SQL to understand what type of data is expected inside each column, and it also identifies how SQL will interact with the stored data.
Each database system has its SQL extension.
For example, SQL Server uses T-SQL, which is a SQL extension. Oracle uses PL-SQL, MySQL and MariaDB use SQL/PSM.
PSM (Persistent Stored Module) is an ISO standard for stored procedures. Teradata and Informix use SPL, and there are several different extensions used by different System Databases.
Suppose you want to perform the queries of SQL language on the stored data in the database, then you are required to install any database management system in your systems, for example, Oracle, MySQL, MongoDB, PostgreSQL, SQL Server, DB2, etc.
For creating a database, there are different commands.
But before we proceed to commands let us know about the database
A database is made up of a collection of tables that store a detailed set of structured data. The tables have collections of rows and columns, referred to as records or tuples, and attributes.
Each column in the table is designed to store a specific type of information, for example, names, dates, dollar amounts, and numbers.
SQL database is the leading Programming language for relational databases and is Ranked No 1 by ANSI (American National Standard Institute). Given below is a list of the famous database:
- Oracle 12c
- Microsoft SQL Server
- SAP HANA
SQL gives commands to the database. The most common SQL commands to manage the database are:
- CREATE – to create a database or tables
- INSERT – to insert new data into a database or tables
- UPDATE – to make adjustments and update data in a database
- DELETE – to remove/delete data from one or more rows from a table
- SELECT – to find/extract or select the attribute based on the conditions from a database
- DROP – removes tables and databases
An SQL engine determines how to perform the task when you execute an SQL command to carry out your request. The Important components of this process are:
- SQL Query Engine
- Optimization Engines
- Query Dispatcher
- Classic Query Engine
A classic query engine allows it to manage all the NoSQL queries.
Knowing SQL basics let us simultaneously learn something about NoSQL.
‘NoSQL’ stands for ‘not only SQL’. A ‘NoSQL database’ typically refers to any non-relational database and stores data in a format other than relational tables. It is an upcoming category of Database Management Systems.
The main characteristic of NoSQL is its non-adherence to Relational Database Concepts. The concept of NoSQL databases grew with internet giants such as Google, Facebook, Amazon, etc. who deal with gigantic volumes of data.
When we use a relational database for massive volumes of data, the system starts getting slow in terms of response time. To overcome this, we normally “scale up” our systems by upgrading our hardware. As an alternative, we distribute our database load on multiple hosts with the load increase, and that is called“scaling out”.
SQL Language elements
Some important elements of SQL language are:
- Keywords: Each SQL statement contains single or multiple keywords.
- Identifiers: Identifiers are names of objects in the database, like user IDs, tables, and columns.
- Strings: Strings can be either literal strings or expressions with VARCHAR or CHAR data types.
- Expressions: Expressions are formed from several elements, like constants, SQL operators, column names, and subqueries.
- Search Conditions: Conditions are used to select a subset of the rows from a table or used to control statements like an IF statement to determine control of flow.
- Special Values: Special values should be used in expressions and as column defaults when building tables.
- Variables: Sybase IQ supports local variables, global variables, and connection-level variables.
- Comments: Comment is another SQL element that is used to attach explanatory text to SQL statements or blocks of statements. The database server does not execute any comment.
- NULL Value: Use NULL, which helps you to specify a value that is unknown, missing, or not applicable.
How SQL Works
SQL lets you work with data at the logical level. You need to be concerned with the implementation details only when you want to manipulate the data. The power of SQL provides benefits to all types of users, including application programmers, database administrators, managers, and end-users.
- It processes sets of data as groups rather than as individual units.
- It provides automatic navigation to the data.
- It uses flow control statements that are complex and powerful individually.
- Flow-control statements are commonly known as Persistent Stored Modules (PSM).
- The PL/SQL extension to Oracle SQL is similar to PSM.
Uses of SQL
There are many uses of SQL, the most common are creation, improvements, and maintenance. It is one of the earliest known database management systems, streamlining the process of data collection, storage, and retrieval.
Both ANSI (American National Standards Institute) and the ISO (International Standards Organisation) have accepted SQL as the standard language for relational databases. When a new standard is published by these organizations, the name of the standard conforms to conventions used by the organization.
SQL statements are used to perform tasks such as updating data on a database or retrieving data from a database.
We can use them in:
- Creating a new database with SQL and inserting new data in the database,
- Modifying or updating previous data and retrieving data from the database,
- Deleting data and creating a new table in one database or even dropping the table,
- Setting permissions for table, procedures, and views, and creating function, views, and stored procedures
16 Parts of SQL
The standard is divided into several parts numbered from 1 to 14. Some of them were never released (part-5 to part-8 and part-12). Leaving the meta-part (part-1) aside, part-2 (the SQL language), part-11 (Information Schema) and part-14 (XML) became widely implemented. Other parts could never come to the mainstream. Part-15 (MDA) has just been released and it will be too early to say whether it will become widespread or not.
The details are as given below:
Part 1 – Framework- A rough overview and some definitions of commonly used terms. The 2011 version of this part is available for free from ISO.
Part 2 – Foundation- Defines most of the SQL languages.
Part 3 – Call-Level Interface (SQL/CLI)- Describes C and COBOL APIs to access SQL databases.
Part 4 – Persistent Stored Modules (SQL/PSM)- Defines a language used for server-side programming (“stored procedures”).
Part 5 – Host Language Bindings (SQL/Bindings)- Merged into part 2 with SQL:2003.
Part 6 – Global Transaction Support (SQL/Transaction)- Never released.
Part 7 – Temporal (SQL/Temporal)- Never released. Temporal support was eventually added to SQL:2011 part 2.
Part 8 – Extended Object Support- Never released. Content absorbed into other parts.
Part 9 – Management of External Data (SQL/MED)- Defines mechanisms to access data stored outside the database.
Part 10 – Object Language Bindings (SQL/OLB)- Defines how to embed SQL statements into Java programs. This is not JDBC, which treats SQL statements as strings.
Part 11 – Information and Definition Schemas (SQL/Schemata)- Defines Information Schema and Definition Schema. which were covered in part 2 before SQL:2003.
Part 12 – Replication (SQL/Replication)- Never released.
Part 13 – Routines and Types Using the Java Programming Language (SQL/JRT)- Defines how to run Java inside the database.
Part 14 – XML-Related Specifications (SQL/XML)- Defines the XML data type and methods to work on XML documents. Appeared with SQL:2003.
Part 15 – Multidimensional arrays (SQL/MDA)- First appeared in 2019.
Part 16 – Property Graph Query (SQL/PGQ)- In progress. Embeds parts of the new GQL-Standard in SQL. Probably release is within 2021 or 2022.
How to use SQL
SQL is used to communicate with a database. As per ANSI, this is the standard language for relational database management systems. SQL commands are used to perform tasks, CREATE, SELECT, DELETE, DROP, INSERT, etc. from a database or a table. SQL syntaxes used in different databases are almost similar. Few RDBMS (Relational Database Management Systems) use a few different commands and even proprietary SQL syntaxes.
We can start using SQL by downloading MySQL software. For this, we have to create our first database and data table.
Using the five basic SQL statements i.e. DDL, DML, DCL, TCL, and DQL we can manage working with our database.
Benefits of using SQL
Following are the main benefits or advantages of using SQL:
- It helps you to access data in the RDBMS system.
- It helps you to describe the data.
- It allows you to define the data in a database and manipulate that specific data.
- With the help of SQL, you can create and drop databases and tables.
- SQL offers you to use the function in a database, create a view, and store procedure.
- You can set permissions on tables, procedures, and views.
Some other important benefits are listed as below:
- Higher Processing Speed: SQL generally operates at a high speed when users explore the database. It helps in retrieving large amounts of data quickly and efficiently.
- Minimal Coding Requirement: SQL is highly user-friendly, i.e. it is easy to use. Someone with no coding experience can easily learn basic SQL coding within a few days. The code structure is also simple, borrowing heavily from English sentences with minimal use of special characters.
- Easier to Manipulate Data: With SQL, it is very easy to view and manipulate the existing data on the database. With a few queries, users can update or change the uploaded information on the database, thus making it helpful for storing dynamic information.
- Easier Data Mining: Among other uses of SQL, it is used for sorting and filtering data by using several queries, making the data more relevant and useful, while reducing redundancy. Under the uses of SQL or MySQL, it is integrally applied to maintain their database. Thus, it becomes easier to navigate if the users are familiar with SQL.
- Restricted Access: SQL is widely considered a safe and protected database. The system is password protected on every device, thus making it difficult for malicious users to use the data without consent.
- Reliable for Complex Queries: SQL is highly-reliable to deliver correct results on complex queries by users, as compared to other Database Management systems.
In this article, we learned about SQL, NoSQL, SQL commands, SQL language elements, and how SQL works. We also learned about 16 parts of SQL, its uses, and how to make use of its various features. We know that SQL is used to query a database, describe, define & manipulate data, and create and drop databases & tables through its commands using statements like DDL, DML, DCL, TCL, and DQL. The database approach has many advantages over flat file-based systems when it comes to storing data.
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We store our data in one form or another. We also use this data in numerous ways to get results. For example, when we log into a company’s website or platform, we provide our details field-wise. These data get stored in their database for further use.
SQL software manages these databases. When you click on the submit button, SQL does its work at the backend and executes a command which instructs the database to store the data. Thus communication between registration form and database is in the language of SQL.
The data type of a column defines what value the column can hold. It can be integer, character, money, date and time, binary, and so on.
It is very simple and easy to learn. SQL is quite manageable and flexible, as it works with information base frameworks from Oracle, IBM, Microsoft, etc. It has a characterized structure and utilizes settled guidelines. It lets you oversee databases without knowing any part of coding.
Knowing SQL is a fundamentally required skill. For a good Software Engineer, having a grip on SQL is an indispensable requirement for landing a Software Engineering job.
NoSQL databases are highly specialized systems and have their special usage and limitations. NoSQL suits more for those who handle huge volumes of data but there is a growing demand for professionals who can handle relational databases (SQL). Thus, learning databases and SQL basics still hold merit.
Relational databases have the following advantages over NoSQL databases:
1. SQL (relational) databases have a mature data storage and management model. This is crucial for enterprise users.
2. SQL database supports the notion of views that allow users to only see data that they are authorized to view. The data that they are not authorized to see is kept hidden from them.
3. SQL databases support stored procedure SQL which allows database developers to implement a part of the business logic into the database.
4. SQL databases have better security models compared to NoSQL databases.
SQL is a great tool for interacting with databases and fetching vital data. Big companies like Netflix, Linkedin, Amazon, Flipkart, Instagram, and most of the Apps and day-to-day services like Ola, Uber use SQL for data collection and analysis for analyzing their performance. Even small startups are employing SQL for similar purposes. Sound knowledge of SQL is essential for a job in data analysis.
Course: To learn SQL, Henry Harvin provides a SQL Developer Course which is immensely effective. There are 7 main modules and 2 curriculum modules to cover the entire course. It is a 16 Hours of Live Online Interactive Classroom Sessions with a guaranteed internship.
Books: Following books are recommended:
1. SQL Tutorial for Beginners: In this SQL Tutorial for beginners PDF, you will learn basic Database concepts, MS-SQL commands, and advanced topics like SQL joins, Create, add and drop a table, etc.
2. SQL in 10 Minutes: This SQL book offers full-color code examples to help you understand how SQL statements are structured. You will also get knowledge of shortcuts and solutions
3. SQL Cookbook: In this SQL book, you will be able to learn the technique of walking a string that allows you to use SQL to parse characters, words, or delimited elements of a string.
4. SQL: The Complete ReferenceThis book includes important Microsoft SQL topics like Window functions, Pivoting rows into columns, reverse-pivoting columns into rows.
5. SQL Pocket Guide: A Guide to SQL UsageThe book teaches you how the systems use SQL functions, regular expression syntax, and type conversion functions.
SQL allows us to handle the information using tables. Most of the databases like SQL Server, Oracle, PostgreSQL, MySQL, MariaDB handle this language with some extensions and variations.
MySQL is a relational database management system based on SQL, which is the most popular language for accessing and managing the records in the database. MySQL is open-source and free software, supported by Oracle.
PL/SQL is a block-structured language with multiple blocks, such as conditional statements, loops, arrays, string, exceptions, collections, records, triggers, functions, procedures, and cursors.