
What is SQL
đź‘‹ Introduction
SQL is a standard language for accessing databases
SQL stands for Structured Query Language
SQL has been an international standard (ISO) since 1987
It is popular and used in many roles in different industries.Â
Example of roles that uses SQL:
- Business Analysts
- Researchers and scientists
- Database administrators
- Data Scientists
- Developers
Want to get started with SQL? Learn and earn a certificate with our SQL Certification Course
Â
SQL Statements
To access a database, you use SQL statements.
The following SQL statement selects all records in a database table called "Customers":
Example
Database Tables
A database most often contains one or more tables.
Each table is identified by a name like "Customers" or "Orders".
Â
Below is a selection from a "Customers" table:
ID | CustomerName | ContactName | Address | City | PostalCode | Country |
---|---|---|---|---|---|---|
1Â | Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
3 | Antonio Moreno TaquerĂa | Antonio Moreno | Mataderos 2312 | MĂ©xico D.F. | 05023 | Mexico |
4Â | Around the Horn | Thomas Hardy | 120 Hanover Sq. | London | WA1 1DP | UK |
5 | Berglunds snabbköp | Christina Berglund | Berguvsvägen 8 | Luleå | S-958 22 | Sweden |
Â
The table above contains five records (one for each customer) and seven columns:
- CustomerID (ID)
- CustomerName
- ContactName
- Address
- City
- PostalCode
- Country
The Most Important SQL Statements:
- SELECTÂ - extracts data from a database
- UPDATEÂ - updates data in a database
- DELETEÂ - deletes data from a database
- INSERT INTOÂ - inserts new data into a database
- CREATE DATABASEÂ - creates a new database
- ALTER DATABASEÂ - modifies a database
- CREATE TABLEÂ - creates a new table
- ALTER TABLEÂ - modifies a table
- DROP TABLEÂ - deletes a table
- CREATE INDEXÂ - creates an index (search key)
- DROP INDEXÂ - deletes an index
SQL keywords are NOT case sensitive: select is the same as SELECT
Â
Learn and earn a certificate with our SQL course 👇

Do you like the blog? Lets us know your thoughts in the comments feed below.
Subscribe to this blog's RSS feed using https://campus.w3schools.com/blogs/blog.atom
Leave a comment