Mark Dixon Page 1 18 – Persistent data storage: relational databases and ADO.
-
date post
21-Dec-2015 -
Category
Documents
-
view
220 -
download
0
Transcript of Mark Dixon Page 1 18 – Persistent data storage: relational databases and ADO.
Mark Dixon Page 2
Question: Self-Contained
• Are the following routines self contained?Dim g
Dim w
Sub Square(ByRef res As Double, ByVal n1 As Double)
res = n1 * n1
End Sub
Function u(num As Double) As Double
Return num * (w + g)
End Function
Mark Dixon Page 3
Session Aims & Objectives• Aims
– To introduce the fundamental ideas involved in using relational databases for persistent data storage
• 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)
– use SQL in your programs to create more complex record-sets
Mark Dixon Page 4
Persistent Data Storage• So far
– programs (web-pages) 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 5
Example: People (analysis)SPECIFICATION
• User Requirements – need to have access to people's details
• Software Requirements– Functional:
–Display list of people from a database– Non-functional
should be viewable anywhere in the world
Mark Dixon Page 6
Record Field
Example: People (Database)
ID Surname Forenames Phone Gender
1 Dixon Mark 01752 232556 Male
2 Smith John 01752 111111 Male
3 Jones Sally 01752 888888 Female
• Information organised into– tables (e.g. person)– fields (e.g. phone)– records (e.g. 1 Dixon Mark 01752 232556 …)
Person
Mark Dixon Page 7
• How many fields?
• How many records?
Questions: Music (Database)
Track Title Artist Name Country
Paranoid Black Sabbath UK
Falling in Love Aerosmith US
Pink Aerosmith US
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
9
3
Mark Dixon Page 8
DBMS• Database Management Systems (DBMS)
provide 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 10
ActiveX Data Objects• ActiveX Data Objects (ADO)
– common database interface• allow you to write code for any DBMS
VB orVB Script
codeADO
MS Access
MS SQL Server
…
…DB front end
Mark Dixon Page 11
Using Record Sets
Const cs = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=D:\People.mdb;"Dim rs As Object 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
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 13
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 (MS Jet 4.0 OLE DB Provider)– Click Next– Select or enter DB name– Click Test Connection button– Click OK– Open with Notepad, cut & paste text
Mark Dixon Page 14
People.aspx
Example: People (rs)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
Mark Dixon Page 15
People.aspx
Example: People (s)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
s
Mark Dixon Page 16
People.aspx
Example: People (recordset)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
s
Mark Dixon Page 17
People.aspx
Example: People (Open)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
s
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 18
People.aspx
Example: Peoplers
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
s
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 19
People.aspx
Example: People (EOF)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
s
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 20
People.aspx
Example: Peoplers
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 21
People.aspx
Example: People (MoveNext)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 22
People.aspx
Example: People (Loop)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 23
People.aspx
Example: People (EOF)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 24
People.aspx
Example: Peoplers
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />Dixon<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 25
People.aspx
Example: People (MoveNext)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 26
People.aspx
Example: People (Loop)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 27
People.aspx
Example: People (EOF)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 28
People.aspx
Example: Peoplers
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />Jones<br />Dixon<br />Smith<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 29
People.aspx
Example: People (MoveNext)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />Jones<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 30
People.aspx
Example: People (Loop)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />Jones<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 31
People.aspx
Example: People (EOF)rs
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
sDixon<br />Smith<br />Jones<br />
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 32
People.aspx
Example: Peoplers
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
Dixon<br />Smith<br />Jones<br />
s
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 33
People.aspx
Example: Peoplers
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
Dixon<br />Smith<br />Jones<br />
s
ID Surname Forenames Phone gender1 Dixon Mark 01752 232556 Male2 Smith John 01752 111111 Male3 Jones Sally 01752 888888 Female
Mark Dixon Page 34
People.aspx
Example: Peoplers
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
Dixon<br />Smith<br />Jones<br />
s
Mark Dixon Page 35
Example: People v2
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String rs = CreateObject("ADODB.Recordset") rs.Open("Person", cs) s = "" Do Until rs.EOF() If rs.Fields("Gender").value = "Male" Then s = s & rs.Fields("Surname").Value & "<br />" End If rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
• Display Surname of Male people:
Mark Dixon Page 36
Example: People v3• Display Surname of Male people:
Sub Page_Load() Const cs = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\People.mdb;" Dim rs As Object Dim s As String Dim sql As String rs = CreateObject("ADODB.Recordset") sql = "SELECT * FROM [Person] WHERE [Gender] = 'Male';" rs.Open(sql, cs) s = "" Do Until rs.EOF() s = s & rs.Fields("Surname").Value & "<br />" rs.MoveNext() Loop parData.InnerHtml = s rs.Close() rs = Nothing End Sub
SQL statement
Mark Dixon Page 37
SQL: Queries• main purpose of databases:
– get information back out: searching
• Structured Query Language– dedicated to interacting with databases
• 3rd Generation Language (such as VB, C++)– code describes how to do task
• 4th Generation Language (such as SQL)– code describes what to do (not how to do it)
Mark Dixon Page 38
SQL: SELECT statement• SELECT statement
– used to get data– can be embedded in VB, via rs.Open:
rs.Open("Person", cs)
rs.Open("SELECT * FROM [Person]", cs)
all fields
Mark Dixon Page 39
SQL: WHERE & ORDER BY• WHERE clause
– used to restrict data
SELECT * FROM [People] WHERE [age]>=18;
• ORDER BY clause– used to change order of data
SELECT * FROM [People] ORDER BY [Surname];
Mark Dixon Page 40
SQL: strings (text data)• Possible confusion:
SELECT * FROM Person WHERE Surname = Smith
this will look for field called Smith - gives error need single (SQL) quotes to signify literal text SELECT * FROM Person WHERE Surname = 'Smith'
Mark Dixon Page 41
SQL & MS access queries• MS Access
– Queries: select data from database– really SQL select statements
– can use queries to test SQL code
MS Access: People.mdb
Mark Dixon Page 42
Questions: SQL• Create an SQL
statement to extract Track Title of records by Aerosmith
Track Title Artist Name Country
Paranoid Black Sabbath UK
Falling in Love Aerosmith US
Pink Aerosmith US
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm
US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness
Disturbed US
Track
SELECT [Track Title] FROM Track WHERE [Artist Name] = 'Aerosmith';
MS Access: Music.mdb
Mark Dixon Page 43
Questions: SQL• Create an SQL
statement to extract all fields of songs by Disturbed, ordered by track name
Track Title Artist Name Country
Paranoid Black Sabbath UK
Falling in Love Aerosmith US
Pink Aerosmith US
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm
US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness
Disturbed US
Track
SELECT * FROM Track WHERE [Artist Name] = 'Disturbed' ORDER BY [Track Title];
MS Access: Music.mdb
Mark Dixon Page 45
SQL: DISTINCT records
SELECT [Artist Name]FROM [Track];
Artist Name
Black Sabbath
Aerosmith
Aerosmith
Aerosmith
Alien Ant Farm
Disturbed
Disturbed
Disturbed
Disturbed
Artist Name
Black Sabbath
Aerosmith
Alien Ant Farm
Disturbed
SELECT DISTINCT [Artist Name]FROM [Track];
Mark Dixon Page 46
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: Get the People v1 example (from the lecture) working.• 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 it displays the data in an html table.• Task 5: Modify your page so that records for males are displayed in blue, and
records for females are displayed in red.• Task 6: Modify your page as per version 4. You will need to:
– Add a form to the page, and three submit buttons– In your code, detect when a button has been pressed (have a look at
previous weeks)• Task 7: Modify your page so that the user can type a letter, and only names
starting with that letter are displayed.• Task 8: Modify your page so that the user can type a series of numerical digits
and only phone numbers containing those digits are displayed.• Task 9: Modify your code so that the user can order the data by surname, or
email address (You may want to use a Query String)