SQL Guide
SQL - Structured Query Language
SQL is a standard computer language for accessing and manipulating databases.
Common database management systems: MySQL, SQL Server, Access, Oracle, Sybase, and DB2
For those who wish to store data in and retrieve data from a database, knowledge of SQL is invaluable.
What is SQL?
- SQL stands for Structured Query Language
- SQL enables us to access databases
- SQL is an ANSI standard computer language
- SQL is used to perform queries on databases
- SQL can retrieve data from databases
- SQL can insert new records into databases
- SQL can delete records from databases
- SQL is easy to learn
SQL Database Tables
A database typically contains one or more tables. Each table is identified by a name (e.g., "Customers" or "Orders"). Tables contain data records (rows).
The following example is a table named "Persons":
| LastName | FirstName | Address | City |
|---|---|---|---|
| Hansen | Ola | Timoteivn 10 | Sandnes |
| Svendson | Tove | Borgvn 23 | Sandnes |
| Pettersen | Kari | Storgt 20 | Stavanger |
The above table contains three records (one for each person) and four columns (last name, first name, address, and city).
SQL Query Procedure
With SQL, we can query a database and get a result set returned.
A query procedure looks like this:
The result set looks like this:
| LastName |
|---|
| Hansen |
| Svendson |
| Pettersen |
How to Learn SQL?
Visit our Complete SQL Tutorial