SQL Syntax
Database Tables
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.
Below is an example of a table called Persons:
P_Id |
LastName |
FirstName |
Address |
City |
1 |
Hansen |
Ola |
Timoteivn 10 |
Sandnes |
2 |
Svendson |
Tove |
Borgvn 23 |
Sandnes |
3 |
Pettersen |
Kari |
Storgt 20 |
Stavanger |
The table above contains three records (one for each person) and five columns (P_Id, LastName, FirstName, Address, and City).
SQL Statements
Most of the actions you need to perform on a database are done with SQL statements.
The following SQL statement will select all the records in the Persons table:
SELECT LastName FROM Persons;
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LastName |
Hansen |
Svendson |
Pettersen |
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Keep in Mind That...
SQL is not case sensitive.
Semicolon after SQL Statements?
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.
The following demonstration may use MySQL database, which does not require to put a semicolon after each SQL statement, but some databases force you to use it.
Demonstration
Below is an SQL test area from W3Schools, which uses the well-known Northwind sample database.
The tables here are for read only because of the problem of embedding the scripts.
For a fully working example, check this by using Chrome.
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The Database includes:
Tablename | Record |
Customers | 91 |
Categories | 8 |
Employees | 10 |
OrderDetails | 518 |
Orders | 196 |
Products | 77 |
Shippers | 3 |
Suppliers | 29 |
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This SQL-Statement is not supported in the WebSQL Database.
The example still works, because it uses a modified version of SQL.
Your browser does not support WebSQL.
Your are now using a light-version of the Try-SQL Editor, with a read-only Database.
If you switch to a browser with WebSQL support, you can try any SQL statement, and play with the Database as much as you like. The Database can also be restored at any time.
Our Try-SQL Editor uses WebSQL to demonstrate SQL.
A Database-object is created in your browser, for testing purposes.
You can try any SQL statement, and play with the Database as much as you like. The Database can be restored at any time, simply by clicking the "Restore Database" button.
W3C WebSQL
WebSQL stores a Database locally, on the user's computer. Each user gets their own Database object.
WebSQL Browser Support
WebSQL is supported in Chrome, Safari, and Opera.
If you use another browser you will still be able to use our Try SQL Editor, but a different version, using a server-based ASP application, with a read-only Access Database, where users are not allowed to make any changes to the data.