Introduction to SQL

on May 20, 2021
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Contents hide
1) What is SQL?
2) What we can do with SQL?
3) SQL Language Support
4) Where We Can Use SQL?
5) Relational Database Management System

What is SQL?

  • The full form of SQL is Structured Query Language.
  • It is a standard language used for accessing and manipulating data from databases.

What we can do with SQL?

  • SQL can execute queries against a database
  • SQL can retrieve data from a database
  • SQL can insert records in a database
  • SQL can update records in a database
  • SQL can delete records from a database
  • SQL can create new databases
  • SQL can create new tables in a database
  • SQL can create stored procedures in a database
  • SQL can create views in a database
  • SQL can set permissions on tables, procedures, and views

SQL Language Support

There are different versions of SQL Language, as SQL is an ANSI/ISO standard.
However, to be compliant with the ANSI standard, All Versions support at least the basic or you can say major commands (e.g: SELECT, UPDATE, DELETE, INSERT, WHERE ) in similar way.

Where We Can Use SQL?

For Building a dynamic website you will need a database.
Requirements:

  • An RDBMS database program (i.e. MS Access, SQL Server, MySQL, Postgres)
  • A server-side scripting language, like PHP, ASP, JavaScript (nodeJS), etc.
  • SQL executer in your server-side scripting language to get the data you want.

So thereafter you can display that data in your UI using HTML and style it via CSS.

Relational Database Management System

  • The short form of Relational Database Management System is RDBMS.
  • RDBMS is the basis for SQL, and for all modern database systems.
  • The data in RDBMS is stored in database objects known as tables. A table is a collection of related data entries and it contains columns and rows.

for example look at the “Customers” table:

SELECT * FROM Customers;

View:
SQL Example Customer Table
Tables have smaller entities called fields. The fields in the Customers table consist of ID, customerNumber, customerName, sales. A field is a column in a table that is designed to maintain specific information about every record in the table.
The row is each individual entry that exists in a table. For example, there are 10 records in the above Customers table. A record is a horizontal entity in a table.