The current webpage is an introduction to SQL on W3Schools. Here’s a summary:

• SQL (Structured Query Language) is the standard language for accessing and manipulating databases.

• SQL lets you:

  • Execute queries and retrieve, insert, update, or delete data from databases.
  • Create new databases, tables, stored procedures, and views.
  • Set permissions on database objects.

• Standardization: SQL is an ANSI/ISO standard, yet most database systems (e.g., MySQL, SQL Server, Oracle) add proprietary extensions.

• Web Integration: To show data from a database on a website, you usually need an RDBMS (like MySQL), a server-side language (such as PHP or ASP), SQL for querying, and HTML/CSS for display.

• RDBMS (Relational Database Management System): The foundation for modern SQL databases. Data is stored in tables, which consist of rows and columns.

  • Example table: A “Customers” table with fields like CustomerID, CustomerName, and City.
  • Rows are called records (individual entries), and columns are called fields (attributes).

• The page also features links to video tutorials, SQL examples, interactive editors, and quizzes for further learning.[1]

1

Learn SQL

SQL is a standard language for storing, manipulating and retrieving data in databases. Our SQL tutorial will teach you how to use SQL in: MySQL, SQL Server, MS Access, Oracle, Sybase, Informix, Postgres, and other database systems.

Introduction to SQL

SQL is a standard language for accessing and manipulating databases.

What is SQL?

• SQL stands for Structured Query Language
• SQL lets you access and manipulate databases
• SQL became a standard of the American National Standards Institute (ANSI) in 1986, and of the International Organization for Standardization (ISO) in 1987

What Can SQL do?

• 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 is a Standard - BUT....

Although SQL is an ANSI/ISO standard, there are different versions of the SQL language.

However, to be compliant with the ANSI standard, they all support at least the major commands (such as SELECT, UPDATE, DELETE, INSERT, WHERE) in a similar manner.

Note: Most of the SQL database programs also have their own proprietary extensions in addition to the SQL standard!

Using SQL in Your Web Site

To build a web site that shows data from a database, you will need:

• An RDBMS database program (i.e. MS Access, SQL Server, MySQL)
• To use a server-side scripting language, like PHP or ASP
• To use SQL to get the data you want
• To use HTML / CSS to style the page

RDBMS

RDBMS stands for Relational Database Management System.

RDBMS is the basis for SQL, and for all modern database systems such as MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

The data in RDBMS is stored in database objects called tables. A table is a collection of related data entries and it consists of columns and rows.

Look at the "Customers" table:

SELECT * FROM Customers;

Every table is broken up into smaller entities called fields. The fields in the Customers table consist of CustomerID, CustomerName, ContactName, Address, City, PostalCode and Country. A field is a column in a table that is designed to maintain specific information about every record in the table.

A record, also called a row, is each individual entry that exists in a table. For example, there are 91 records in the above Customers table. A record is a horizontal entity in a table.

A column is a vertical entity in a table that contains all information associated with a specific field in a table.