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.
In this tutorial we will use the well-known Northwind sample database (included in MS Access and MS SQL Server).
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;
Why semicolon is used after SQL statements:
Semicolon is used to separate SQL statements. It is a standard way to separate SQL statements in a database system in which more than one SQL statements are used in the same call.
In this tutorial, we will use semicolon at the end of each SQL statement.
SELECT - extracts data from a databaseUPDATE - updates data in a databaseDELETE - deletes data from a databaseINSERT INTO - inserts new data into a databaseCREATE DATABASE - creates a new databaseALTER DATABASE - modifies a databaseCREATE TABLE - creates a new tableALTER TABLE - modifies a tableDROP TABLE - deletes a tableCREATE INDEX - creates an index (search key)DROP INDEX - deletes an index