1. Interacting With Data
Databases

2. Database Management System
Store, manage, retrieve data
Applies database and security rules
DBMS Server
Computation, Replication/Backup
Interprets SQL Queries
DBMS is a group of software applications designed to provide a variety of functions for Data and the applications that access the data.

3. Structure of a Data Table
Table Name
Students
Column (Field)
Studentno Name Address Phone
Row (Record)
White 9 White St
Brown 6 Brown Rd
Smith 2 Smith St
Information is added to data table on a Row by Row basis
Table names and Column names are case sensitive

4. Databases
Two main types of Database structures used in this course. The Flat File model and the Relational Model.
Flat File – Based on a single table.
Simple but inefficient for complex data
storage and retrieval.
Relational – multiple tables in single database
More efficient, but harder to create and organize.
Has been the standard model for several
decades.

5. Database (Flat File) - Data Table
The Flat File data model relies on a single table to hold all data about a particular subject.
The data table can become very large and difficult to manage
The common Telephone Book is a classic example of a Flat-File database
Very few serious applications rely on this database model.

6. Flat-File Model Students
Columns are duplicated, increasing table size
Studentno Name Address Phone
Course1
Mark1
Course2
Mark2
White White St INT DCN
Brown Brown Rd IOS ULI
Smith Smith St IOS HWD
In complex databases, the Flat-File model cannot avoid duplication of Column data.
Searching, updating and deleting data becomes very difficult

7. How Data Flows
ODBC Connection Interpreter (DSN) (Translates client request so DBMS understands what the client wants)
Client Browser
Sends Recordset request by way of Connection Object
Sends and receives Query request by way of Recordset Object
Database Management System (Applies rules and searches for data)
Data Tables (contains all information)
Search for Data (SQL query)
Create recordset based on data found
Recordsets (contains copy of information requested by client)

8. How Data Flows
ODBC Connection Interpreter (DSN) (Translates client request so DBMS understands what to do)
Open Database Connectivity provides a standard software interface to different database management systems (DBMS).
Software applications can communicate with different DBMSs without altering their applications by using drivers provided by Database system vendors
DSNs (data source name) are set up to use drivers, either by;
1) accessing the ODBC applet in the control panel or,
2) writing a DSN-less connection string (handy when you do not have access to the control panel or when the O/S does not have a control panel)
A Connection Object is created which allows the application to connect to the database System

9. Creating The Connection Object
How Data Flows
Creating The Connection Object
The Connection Object can be created either as a DSN or DSN-less connection
DSN Connection
<%
‘create the object (DSN already set in the control panel) that will connect to the database
Set conn = CreateObject (“ADODB.Connection”)
‘ open the connection
conn.Open “INT213con”
%>
DSN-less Connection
<%
‘create the object without DSN being setup in control panel
Set conn = CreateObject (“ADODB.Connection”)
‘ create the connection
conn.ConnectionString="DRIVER={Microsoft Access Driver (*.mdb)};" &_
"DBQ=C:\Inetpub\wwwroot\INT213db.mdb“
‘Open the connection
conn.Open
%>

10. Recordsets (contains information requested by client)
Recordset Object
Recordsets (contains information requested by client)
Recordset Object sends a query to the database system using the Connection Object.
The DBMS processes the query and returns the data requested in the form of Rows and Columns (just like an Excel spreadsheet).
The Recordset and the data it contains is a copy (snapshot) of the data from the data tables. It is held in RAM on the client system. This data can be displayed, altered, deleted, etc. Any changes are sent back to the server using the Recordset Object
The actual data tables will not be affected by changes until the Recordset is written back to the Data Tables.

11. Recordset Object Creating Recordsets
'set SQL statement that will search for all data in the database Table you created in Access
sql = "SELECT * FROM students"
'Establish the recordset which will hold a copy of the retrieved data in memory
Set rs = Server.CreateObject("ADODB.RecordSet")
'Open the recordset using the Server connection
rs.Open sql, conn

12. The Whole Thing - Together
<% Option Explicit %>
<%
Dim conn, rs, sql, path, StuNo, StuPhone
Set conn = Server.CreateObject("ADODB.Connection")
‘Open the connection
conn.Open “INT213con”
'set SQL statement that will search for all data in the database Table you created in Access
sql = "SELECT * FROM students"
'Establish the recordset which will hold a copy of the retrieved data in memory
Set rs = Server.CreateObject("ADODB.RecordSet")
'Open the recordset using the Server connection
rs.Open sql, conn
Place the data into variables before closing the Recordset.
StuNo = rs(“Studentno”)
StuPhone = rs(“Phone”)
'Close the connection to Server and Recordset
rs.close
set rs = nothing
conn.close
set conn = nothing
%>

13. SQL Looking for Data in All the Right Places
Using the Students Table, lets see what some SQL queries can do
Select * From Students
Select * From Students Where Studentno <>
Select Phone, Name From Students Order By Studentno
Select * From Students Order by Name DESC
SQL is the language of Database Systems. It is extremely powerful, but the logic of its’ use is easy to understand. SQL is a course in itself, so we will only deal with very basic issues in this course.

14. Combining SQL with Form Data
Dynamic web sites require input from users who want specific data from a database.
To retrieve this data it will be necessary to combine an SQL statement with the Request object.
Data = “Select * from Students Where Name = ‘” & Request(”txtname”) & “’”
Note the Single quotes. They protect the double quotes that are added by the Text Box. The single quotes act as an extra set of double quotes.