SQL tutorial provides basic and advanced concepts of SQL. Our SQL tutorial is designed for both beginners and professionals.
SQL (Structured Query Language) is used to perform operations on the records stored in the database, such as updating records, inserting records, deleting records, creating and modifying database tables, views, etc.
SQL is not a database system, but it is a query language.
Suppose you want to perform the queries of SQL language on the stored data in the database. You are required to install any database management system in your systems, for example, Oracle, MySQL, MongoDB, PostgreSQL, SQL Server, DB2, etc.
What is SQL?
SQL is a short-form of the structured query language, and it is pronounced as S-Q-L or sometimes as See-Quell.
This database language is mainly designed for maintaining the data in relational database management systems. It is a special tool used by data professionals for handling structured data (data which is stored in the form of tables). It is also designed for stream processing in RDSMS.
You can easily create and manipulate the database, access and modify the table rows and columns, etc. This query language became the standard of ANSI in the year of 1986 and ISO in the year of 1987.
If you want to get a job in the field of data science, then it is the most important query language to learn. Big enterprises like Facebook, Instagram, and LinkedIn, use SQL for storing the data in the back-end.
Nowadays, SQL is widely used in data science and analytics. Following are the reasons which explain why it is widely used:
History of SQL
"A Relational Model of Data for Large Shared Data Banks" was a paper which was published by the great computer scientist "E.F. Codd" in 1970.
The IBM researchers Raymond Boyce and Donald Chamberlin originally developed the SEQUEL (Structured English Query Language) after learning from the paper given by E.F. Codd. They both developed the SQL at the San Jose Research laboratory of IBM Corporation in 1970.
At the end of the 1970s, relational software Inc. developed their own first SQL using the concepts of E.F. Codd, Raymond Boyce, and Donald Chamberlin. This SQL was totally based on RDBMS. Relational Software Inc., which is now known as Oracle Corporation, introduced the Oracle V2 in June 1979, which is the first implementation of SQL language. This Oracle V2 version operates on VAX computers.
Process of SQL
When we are executing the command of SQL on any Relational database management system, then the system automatically finds the best routine to carry out our request, and the SQL engine determines how to interpret that particular command.
Structured Query Language contains the following four components in its process:
A classic query engine allows data professionals and users to maintain non-SQL queries. The architecture of SQL is shown in the following diagram:
Some SQL Commands
The SQL commands help in creating and managing the database. The most common SQL commands which are highly used are mentioned below:
This command helps in creating the new database, new table, table view, and other objects of the database.
This command helps in updating or changing the stored data in the database.
This command helps in removing or erasing the saved records from the database tables. It erases single or multiple tuples from the tables of the database.
This command helps in accessing the single or multiple rows from one or multiple tables of the database. We can also use this command with the WHERE clause.
This command helps in deleting the entire table, table view, and other objects from the database.
This command helps in inserting the data or records into the database tables. We can easily insert the records in single as well as multiple rows of the table.
SQL vs No-SQL
The following table describes the differences between the SQL and NoSQL, which are necessary to understand:
Advantages of SQL
SQL provides various advantages which make it more popular in the field of data science. It is a perfect query language which allows data professionals and users to communicate with the database. Following are the best advantages or benefits of Structured Query Language:
1. No programming needed
SQL does not require a large number of coding lines for managing the database systems. We can easily access and maintain the database by using simple SQL syntactical rules. These simple rules make the SQL user-friendly.
2. High-Speed Query Processing
A large amount of data is accessed quickly and efficiently from the database by using SQL queries. Insertion, deletion, and updation operations on data are also performed in less time.
3. Standardized Language
SQL follows the long-established standards of ISO and ANSI, which offer a uniform platform across the globe to all its users.
The structured query language can be easily used in desktop computers, laptops, tablets, and even smartphones. It can also be used with other applications according to the user's requirements.
5. Interactive language
We can easily learn and understand the SQL language. We can also use this language for communicating with the database because it is a simple query language. This language is also used for receiving the answers to complex queries in a few seconds.
6. More than one Data View
The SQL language also helps in making the multiple views of the database structure for the different database users.
Disadvantages of SQL
With the advantages of SQL, it also has some disadvantages, which are as follows:
The operation cost of some SQL versions is high. That's why some programmers cannot use the Structured Query Language.
2. Interface is Complex
Another big disadvantage is that the interface of Structured query language is difficult, which makes it difficult for SQL users to use and manage it.
3. Partial Database control
The business rules are hidden. So, the data professionals and users who are using this query language cannot have full database control.