Mark Dixon Page 1 17 – Persistent data storage: relational databases and ADO

Mark Dixon Page 2 Session Aims & Objectives Aims –To introduce the fundamental ideas involved in persistent data storage and relational databases Objectives, by end of this week’s sessions, you should be able to: –create a relational database table –create a web page (ASP) that displays data from a single table in a database using ActiveX Data Objects (ADO)

Mark Dixon Page 3 Persistent Data Storage So far –all programs lose data when closed Not realistic –typically data stored to persistent storage device (e.g. hard disk, key drive, floppy disk, CD-RW) Use either –flat files –database (relational, or object oriented)

Mark Dixon Page 4 Example: People (Specification) User requirement: –Display list of people from database online How: –Combine our knowledge of: ASP (active server pages) ADO (activeX data objects)

Mark Dixon Page 5 Record Field Example: People (Database) IDSurnameForenamesPhone 1DixonMark SmithJohn JonesSally BloggsFred JohnsonGenny01752 Information organised into –tables (e.g. person) –fields (e.g. phone) –records (e.g. 1 Dixon Mark …) Person

Mark Dixon Page 6 How many fields? How many records? Example: Music (Database) Track TitleArtist NameCountry ParanoidBlack SabbathUK Falling in LoveAerosmithUS PinkAerosmithUS Love in an ElevatorAerosmithUS Smooth CriminalAlien Ant FarmUS Meaning of LifeDisturbedUS The GameDisturbedUS VoicesDisturbedUS Down with the SicknessDisturbedUS Track

Mark Dixon Page 7 Database Management Systems DBMS provides facilities for: –creating and changing databases add/remove records add/remove fields add/remove data –For example: Microsoft Access dBase Borland Paradox MySQL Microsoft SQL Server Oracle home/small business large scale

Mark Dixon Page 8 MS Access Music database

Mark Dixon Page 9 ActiveX Data Objects (what & why) ActiveX Data Objects (ADO) –common database interface allow you to write code for any DBMS VB or VB Script code ADO MS Access MS SQL Server … … DB front end

Mark Dixon Page 10 ADO Record Set Object Used to interact with tables Properties –BOF: true if at start of record set (before first record) –EOF: true if at end of record set (after last record) –Fields: used to get and set data values Methods –Open: used to open record set –MoveFirst: moves focus to first record –MovePrevious: moves focus to previous record –MoveNext: moves focus to next record –MoveLast: moves focus to last record –Close: closes record set

Mark Dixon Page 11 Using Record Sets <% Const cs = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=D:\Music.mdb; Persist Security Info=False" Dim rs rs = CreateObject ("ADODB.Recordset") rs. Open ("Person", cs) Do Until rs.EOF() … rs. MoveNext() Loop rs. Close() rs = Nothing %> Connection string – identify database Open record set with table Move to next record Close record set

Mark Dixon Page 12 Connection Strings: UDL files Generate connection strings –Right click on desktop –Select New, Text Document –Rename to *.UDL (Yes to warning message) –Double click –Select provider –Click Next –Select or enter DB name –Click Test Connection button –Click OK –Open with Notepad, cut & paste text

Mark Dixon Page 13 People.aspx Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs

Mark Dixon Page 14 People.aspx Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs

Mark Dixon Page 15 People.aspx Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs

Mark Dixon Page 16 Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs Dixon People.aspx

Mark Dixon Page 17 Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs Dixon Smith People.aspx

Mark Dixon Page 18 Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs Dixon Smith Jones People.aspx

Mark Dixon Page 19 Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs Dixon Smith Jones Bloggs People.aspx

Mark Dixon Page 20 Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs Dixon Smith Jones Bloggs Anderson People.aspx

Mark Dixon Page 21 Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs Dixon Smith Jones Bloggs Anderson People.aspx

Mark Dixon Page 22 People.aspx Example: People Personal Address Book Personal Address Book <% Const cs = " Provider=…;Data Source=D:\People.mdb; " Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing %> rs

Mark Dixon Page 23 Example: People v2 Const cs = "Provider=…;Data Source=D:\People.mdb;" Sub DisplayPeople() Dim rs rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) Do Until rs.EOF() Response.Write(rs.Fields("Surname").Value) Response.Write(" ") rs.MoveNext() Loop rs.Close() rs = Nothing End Sub Personal Address Book Personal Address Book <% DisplayPeople() %> Use procedure to separate: –code detail –html

Mark Dixon Page 24 Tutorial Exercise: People Task 1: Create your own People database: –Open MS Access –Create a new database file –Create a new table –Create fields –Enter data Task 2: Create the People v2 asp page (as per the lecture) to display data from the database. Task 3: Modify your page so that it displays phone number as well as the person's name. Task 4: Modify your page so that the user can type a letter, and only names starting with that letter are displayed. Task 5: Modify your page so that the user can type a series of numerical digits and only phone numbers containing those digits are displayed. Task 6: Modify your page so that it displays the data in an html table. Hint: use Response.Write to insert the appropriate tags.

Mark Dixon Page 25 Tutorial Exercise: Music Task 1: Create your own Music Database. Task 2: Create an asp page to display data from this database. Task 3: Modify your page so that the user can type the name of an artist, and only tracks by that artist are displayed Task 4: Make your page case in-sensitive (i.e. UPPER or lower case makes no difference)