A database most often contains one or more tables. Every table is identified by a name (e.g.
"Customers" or "Purchases"). Tables contain records (rows) with data.
Below is an example of a table called "Persons":
The table above contains three records (one for each person) and five columns (P_Id, LastName,
FirstName, Address, and City).
Most of the actions you need to perform on a database are done with SQL statements.
The Below SQL statement will select all the records in the "Persons" table:
In this tutorial we will teach you all about the different 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.
We are using MS Access and SQL Server 2000 and we do not have to put a semicolon after each SQL
statement, but some database programs force you to use it.
SQL can be divided into two parts: The Data Manipulation Language (DML) and the Data Definition
The query and update commands form the DML part of SQL:
The DDL part of SQL permits database tables to be created or deleted. It also define indexes
(keys), specify links between tables, and impose constraints between tables. The most important
DDL statements in SQL are:
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