![Page 1: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/1.jpg)
Data files and databases
![Page 2: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/2.jpg)
Data files and databases
• Need a control to browse to a file• Standard controls for drive folder and list not
much use• The CommonDialogs control offers
– drive folder file browse to select file– print– font select– colour select
• But you need to add it in..
![Page 3: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/3.jpg)
Adding components
![Page 4: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/4.jpg)
Using the Common Dialog Control
Private Sub Command1_Click()CommonDialog1.ShowOpenMsgBox ("You selected " & CommonDialog1.FileName).. code to process FileNameEnd Sub
![Page 5: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/5.jpg)
File open exercise
Program to browse and display graphics filesUse a common dialog control to select graphics filesSet the filter of the dialog to something like: Image files | *.bmp; *.jpg; *.jpeg | All files | *.*Display the selected image in a Picture control (see graphics)
![Page 6: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/6.jpg)
VB data file ideas 2 modes –
• sequential (work through file start to end - character (external format))
• random (can move back and forth through file, binary (internal format) )
![Page 7: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/7.jpg)
Sequential – write # and input#
Open "c:\walter\vb\filing\test1.dat" For Output As #1Write #1, 1, 2, 3.1, "Test1", "Test2"Close #1
Open "c:\walter\vb\filing\test1.dat" For Input As #1Input #1, x, y, z, a, bClose #1
![Page 8: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/8.jpg)
Sequential – Print # and Line Input#Open "c:\walter\vb\filing\test1.dat" For Output As #1Print #1, 1, 2, "Test1"Close #1
Open "c:\walter\vb\filing\test1.dat" For Input As #1Line Input #1, xClose #1
MsgBox (x)
![Page 9: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/9.jpg)
Exercise – sequential filing
1. Fill an array with 100 random integers2. Save them into a file ( write# )3. Read file back ( input# ) into a second array4. Check arrays have same content
![Page 10: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/10.jpg)
Random
• Data in file as records• Must define size of record (fixed length good)• Can then seek to nth record • And read or write it
![Page 11: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/11.jpg)
User-defined type (record)Private Type myRecordpayroll As Integerdepartment As Integername As String * 14End Type
fixed length string
length of record = 2 + 2 + 14 = 18 bytes
![Page 12: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/12.jpg)
Writing to random access file
Dim emp As myRecordemp.payroll = 23emp.department = 3emp.name = "Fred"Open "c:\walter\vb\filing\test.dat" For Random As #1 Len = 18Put #1, 1, empemp.payroll = 17emp.department = 6emp.name = "John"Put #1, 2, empPut #1, 3, empClose #1
result on next slide
record position 1
![Page 13: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/13.jpg)
Random file contents
record 1 record 2 record 3
2 bytes = integer = 23
2 bytes = 1 integer = 3
string padded with spaces to length 14
![Page 14: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/14.jpg)
Reading Random File
Dim emp As myRecordOpen "c:\walter\vb\filing\test.dat" For Random As #1 Len = 18Get #1, 2, empClose #1MsgBox (emp.payroll & " " & emp.department & " " &_ emp.name)
read second record
![Page 15: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/15.jpg)
Binary = random with record size 1Dim b As ByteOpen "c:\walter\vb\filing\test.dat" For Binary As #1For bytePosition = 1 To 10 Get #1, bytePosition, b Debug.Print bNextClose #1
![Page 16: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/16.jpg)
Exercise – data file
• Using binary mode, write the characters A to Z into a file (ASCII 65 on)
• Then read them back in reverse ie byte position 26 first
• Debug.print them out
![Page 17: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/17.jpg)
Working with a database – the hard way
![Page 18: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/18.jpg)
Working with a database – the hard way
![Page 19: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/19.jpg)
Working with a database – the hard way
Private Sub Command1_Click()Data1.Recordset.DeleteData1.RefreshEnd Sub
![Page 20: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/20.jpg)
Working with a database – the wizardAddins..Addin Manager
![Page 21: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/21.jpg)
Working with a database – the wizard
![Page 22: Data files and databases. Need a control to browse to a file Standard controls for drive folder and list not much use The CommonDialogs control offers](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649ee65503460f94bf65d7/html5/thumbnails/22.jpg)
Exercise – database access
• Use Access to produce a simple database with just one table – personnel = ID name and department number (Access97 format)
• In a VB project have two forms– one with a data control, hand-coded
(explore insert delete buttons)– one created by the Data Form Wizard