A database most often contains one or more tables. Each table is identified by a name (e.g. "Customers" or "Orders"). Tables contain records (rows) with data.
In this tutorial we will use the well-known Northwind sample database (included in MS Access and MS SQL Server).
Below is a selection from the "Customers" table:
|Obere Str. 57||Berlin||12209||Germany|
|2||Ana Trujillo||Avda. de la |
|3||Antonio||Mataderos 2312||México D.F.||05023||Mexico|
|4||Around the Horn||120 Hanover Sq.||London||WA1 1DP||UK|
|5||Berglunds snabbköp||Berguvsvägen 8||Luleå||S-958 22||Sweden|
The table above contains five records (one for each customer) and seven columns (CustomerID, CustomerName, ContactName, Address, City, PostalCode, and Country).
Most of the actions you need to perform on a database are done with SQL statements.
The following SQL statement selects all the records in the "Customers" table:
SELECT * FROM Customers;
In this tutorial we will teach you all about the different SQL statements.
In this tutorial we will write all SQL keywords in upper-case.
Some database systems require a semicolon at the end of each SQL statement.
Semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server.
In this tutorial, we will use semicolon at the end of each SQL statement.