SQLGuide
SQL - Structured Query Language
SQL is the standard computer language used to access and process databases.
Common database management systems: MySQL, SQL Server, Access, Oracle, Sybase, and DB2
For those who want to store data in and retrieve data from databases, SQL knowledge is invaluable.
What is SQL?
- SQL refers to Structured Query Language (Structured Query Language)
- SQL gives us the ability to access databases
- SQL is an ANSI standard computer language
- SQL executes queries against databases
- SQL can retrieve data from a database
- SQL can insert new records into a database
- SQL can delete records from a database
- SQL is very easy to learn
SQL Database Tables
A database usually contains one or more tables. Each table is identified by a name (for example, "Customers" or "Orders"). Tables contain records (rows) with data.
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 table above contains three records (each one corresponding to a person) and four columns (Last Name, First Name, Address, and City).
SQL Query Programs
With SQL, we can query a database and obtain a returned result set.
A query program looks like this:
The result set looks like this:
| LastName |
|---|
| Hansen |
| Svendson |
| Pettersen |
How to learn SQL?
Visit usComplete SQL Tutorial
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