To Learn SQL this SQL tutorial explains both basic and advanced ideas about SQL. Our SQL tutorial is made for both newbies and experienced SQL users.
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 a query language, not a database system.
Let’s say you want to use the SQL language to do queries on the data stored in the database. You must install a database management system, such as Oracle, MySQL, MongoDB, PostgreSQL, SQL Server, DB2, etc., on your systems.
What is SQL?
SQL is an abbreviation for “structured query language.” It can be pronounced S-Q-L or sometimes “See-Quell.”
This database language is mostly made for keeping data in relational database management systems up to date. It is a special tool that people who work with structured data use (data which is stored in the form of tables). It is also designed for stream processing in RDSMS.
You can easily create and change the database, get to the table rows and columns and change them, and so on. This query language was chosen as the standard by ANSI in 1986 and by ISO in 1987.
It is the most important query language to learn if you want to work in the field of data science. SQL is used by big businesses like Facebook, Instagram, and LinkedIn to store data on the back end.
Why SQL?
SQL is used a lot in data science and analytics these days. Here are some of the reasons why it is used so often:
Data professionals and other SQL users use SQL mostly to add, change, and remove data from a relational database.
SQL lets people who work with data and people who use the data get the data from relational database management systems.
- It also helps them explain the way the data is set up.
- It lets SQL users make, delete, and change the database and tables.
- It also helps make the view, stored procedure, and functions in the relational database.
- It allows you to define the data and modify that stored data in the relational database.
- It also allows SQL users to set the permissions or constraints on table columns, views, and stored procedures.
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. made their first SQL programme based on the ideas of E.F. Codd, Raymond Boyce, and Donald Chamberlain. This SQL was based on RDBMS in every way. In June 1979, Relational Software Inc., which is now called Oracle Corporation, released the Oracle V2. This was the first programme to use the SQL language. This version of Oracle V2 works on VAX computers.
Process of SQL
When we run a SQL command on a Relational database management system, the system automatically finds the best way to do what we want, and the SQL engine figures out how to interpret that command.
Structured Query Language is made up of four parts that work together:
Search for Dispatcher
Engines for Optimization
The first search engine
SQL Query Engine, and so on.
A classic query engine lets both people who work with data and people who use it run non-SQL queries. The following picture shows how SQL is put together:
Some commands for SQL
The SQL commands help make the database and run it. Here are some of the most common SQL commands that are used often:
- CREATE command
- UPDATE command
- DELETE command
- SELECT command
- DROP command
- INSERT command
CREATE command
This command lets you make a new database, table, table view, and other database objects.
UPDATE command
This command can be used to change or update the data that is stored in the database.
DELETEcommand
This command helps get rid of or delete the records that have been saved in the database tables. It gets rid of one or more tuples from the database tables.
SELECT command
This command lets you get to a single row or multiple rows from one or more database tables. This command can also be used with the WHERE clause.DRO
DROP command
This command lets you delete an entire table, table view, or other object from the database.
INSERT command
This command helps add data or records to the database tables. We can easily add records to a single row or to several rows at once.
SQL vs No-SQL
The differences between SQL and NoSQL, which are important to know, are shown in the table below:
| SQL | No-SQL |
|---|---|
| 1. SQL is a relational database management system. | 1. No-SQL is a database management system that is not relational or distributed. |
| 2. This database system’s query language is a structured query language. | 2. The query language used in No-SQL database systems is non-declarative in nature. |
| 3. SQL database schema is predefined, fixed, and static. | 3. The No-SQL database schema is a dynamic schema for unstructured data. |
| 4. These databases can be scaled vertically. | 4. These databases can be scaled horizontally. |
| 5. SQL databases are in the form of tables, which contain rows and columns. | 5. No-SQL databases are in the form of documents, key-value pairs, and graphs. |
| 6. It adheres to the ACID model. | 6. It adheres to the BASE model. |
| 7. The SQL database makes it simple to manage complex queries. | 7. NoSQL databases are incapable of handling complex queries. |
| 8. This database is not ideal for storing hierarchical data. | 8. While NoSQL databases are ideal for storing hierarchical data. |
| 9. Object-relational mapping is required for all SQL databases. | 9. Object-relational mapping is not required in many No-SQL databases. |
| 10. The top enterprises that use this query language include Gauges, CircleCI, Hootsuite, and others. | 11. The top companies that use this query language are Airbnb, Uber, and Kickstarter. |
| 12.SQL database systems include SQLite, MS-SQL, Oracle, PostgreSQL, and MySQL. | 12. NoSQL database systems include Redis, MongoDB, Hbase, BigTable, CouchDB, and Cassandra. |
Advantages of SQL
SQL is becoming more popular in the field of data science because it has many benefits. It is a perfect query language that lets both people who work with data and people who use the database talk to it. Here are some of the best things about Structured Query Language:
1. No coding is needed
SQL doesn’t need a lot of lines of code to manage the database systems. Using simple SQL syntax rules, we can easily get to the database and keep it up to date. SQL is easy to use because of these simple rules.
2. Queries that are processed quickly
Using SQL queries, it is quick and easy to get a lot of information from the database. Data operations like adding, removing, and changing take less time as well.
3. Languages that are the same
SQL is based on the ISO and ANSI standards, which have been around for a long time and give all of its users a uniform platform around the world.
4. Portability
The structured query language is easy to use on desktop computers, laptops, tablets, and even smartphones. It can also be used with other programmes based on the needs of the user.
5.Interactive language
The SQL language is easy to learn and understand. This language is also a simple query language, so we can use it to talk to the database. This language is also used to get quick answers to very complicated questions.
6. More than one view of the data
The SQL language can also be used to give different database users different views of how a database is set up.
Disadvantages of SQL
SQL has some good points, but it also has some bad points, which are:
1. Cost
Some versions of SQL have high costs to run. Some programmers can’t use the Structured Query Language because of this.
2. Interface is difficult
Another big problem with Structured Query Language is that it has a hard-to-use interface. This makes it hard for SQL users to use and manage.
3. Partial Database control
The rules of the business are hidden. So, data experts and users who use this query language can’t have full control over the database.