在VB6中用 Select 语句检索记录
作者：unknown 更新时间： 2005-05-02
本文向你介绍如何不用借助Access，直接在程序中创建一个数据库，然后从标准的ASCII文本文件中读取数据到数据库中。原文是微软知识库中的一篇文章，但当时是针对VB3写的，所以其中的代码有点过时。例如现在DAO中已没有Table对象，代之以Recordset对象。下面是修改后的代码，在VB6中调试通过。
首先在工程中添加对Microsoft DAO 3.51 Library引用。
在窗体中添加三个命令按钮和两个MSFlexGrid.
按照下表设置和控件的属性：
控件 属性 值
Command1 Caption "建立文本文件并显示在网格中"
Command2 Caption "传输入数据并新建一个数据库"
Command3 Caption "显示新数据库中的数据"
Grid1 Cols 5
Grid1 Rows 35
Grid2 Cols 5
Grid2 Rows 35
将下面的代码添加到窗体的声明部分
Dim nums(30) As Long
Dim names(30) As String * 20
Dim addresses(30) As String * 25
Dim ss_nums(30) As String * 12
Const DB_LONG = 4
Const DB_TEXT = 10
Const DB_LANG_GENERAL =
";LANGID=0x0809;CP=1252;COUNTRY=0"
将下面的代码添加到窗体的Load事件中
Sub Form_Load ()
Show
grid1.ColWidth(1) = 1000 'For Emp ID
grid1.ColWidth(2) = 2000 'For Emp Name
grid1.ColWidth(3) = 3000 'For Emp Addr
grid1.ColWidth(4) = 2000 'For Emp SSN
grid1.Col = 1
grid1.Row = 0
grid1.Text = "Emp ID" 'Header for Emp ID from text
file
grid1.Col = 2
grid1.Row = 0
grid1.Text = "Emp Name" 'Header for Emp Name from text
file
grid1.Col = 3
grid1.Row = 0
grid1.Text = "Emp Addr" 'Header for Emp Addr from text
file
grid1.Col = 4
grid1.Row = 0
grid1.Text = "Emp SSN" 'Header for Emp SSN from text
file
grid2.ColWidth(1) = 1000 'For Emp ID
grid2.ColWidth(2) = 2000 'For Emp Name
grid2.ColWidth(3) = 3000 'For Emp Addr
grid2.ColWidth(4) = 2000 'For Emp SSN
grid2.Col = 1
grid2.Row = 0
grid2.Text = "Employee ID" 'Header for Emp ID from DB
grid2.Col = 2
grid2.Row = 0
grid2.Text = "Employee Name" 'Header for Emp Name from
DB
grid2.Col = 3
grid2.Row = 0
grid2.Text = "Employee Addr" 'Header for Emp ID from
DB
grid2.Col = 4
grid2.Row = 0
grid2.Text = "Employee SSN" 'Header for Emp Name from
DB
End Sub
在Command1_Click事件中加入下面的代码
Sub Command1_Click ()
For i% = 1 To 30
nums(i%) = i%
names(i%) = "John Doe # " + Str$(i%)
addresses(i%) = Str$(i%) + " Mocking Bird Lane"
If i% < 9 Then
'* Enter the following four lines as one, single line:
ss_nums(i%) = Trim$(Str$(i%) + Trim$(Str$(i%))+
Trim$(Str$(i%)) + "-" + Trim$(Str$(i% + 1))+
Trim$(Str$(i% + 1)) + "-" + Trim$(Str$(i%))
+ Trim$(Str$(i%)) + Trim$(Str$(i%)) + Trim$(Str$(i%)))
Else
'* Enter the following two lines as one, single line:
ss_nums(i%) = Trim$(Trim$(Str$(999)) + "-" +
Trim$(Str$(88))+ "-" + Trim$(Str$(7777)))
End If
Next i%
Open "Testdata.DAT" For Output As #1
For j% = 1 To 30
Print #1, nums(j%)
Print #1, names(j%)
Print #1, addresses(j%)
Print #1, ss_nums(j%)
Next j%
Close #1
For i% = 1 To 30 'Display results from text file
grid1.Col = 1
grid1.Row = i%
grid1.Text = nums(i%) 'Load Emp IDs
grid1.Col = 2
grid1.Row = i%
grid1.Text = names(i%) 'Load Emp Names
grid1.Col = 3
grid1.Row = i%
grid1.Text = addresses(i%) 'Load Emp Addrs
grid1.Col = 4
grid1.Row = i%
grid1.Text = ss_nums(i%) 'Load Emp SSNs
Next i%
End Sub
在Command2_Click事件中加入下面的代码
Sub Command2_Click ()
Dim newdb As Database
Dim newtb As Recordset
Dim newtd As New tabledef
Dim newidx As New Index
Dim field1 As New field 'For Emp nums
Dim field2 As New field 'For Emp names
Dim field3 As New field 'For Emp addresses
Dim field4 As New field 'For Emp ss_nums
screen.MousePointer = 11 'Display the time to build
Set newdb = CreateDatabase("NEWDB.MDB",
DB_LANG_GENERAL)
newtd.Name = "Emp_Table" '* New table name
field1.Name = "Emp_ID" '* Holds Employee ID nums()
field1.Type = DB_LONG
newtd.Fields.Append field1
field2.Name = "Emp_Name" '* Holds Emp names()
field2.Type = DB_TEXT
field2.Size = 20
newtd.Fields.Append field2
field3.Name = "Emp_Addr" '* Holds Employee addr()
field3.Type = DB_TEXT
field3.Size = 25
newtd.Fields.Append field3
field4.Name = "Emp_SSN" '* Holds emp ss_nums()
field4.Type = DB_TEXT
field4.Size = 12
newtd.Fields.Append field4
newidx.Name = "Emp_ID_IDX" '* You have to have an
index
newidx.Fields = "Emp_ID"
newidx.Primary = True
newtd.Indexes.Append newidx
newdb.TableDefs.Append newtd
Set newtb = newdb.OpenRecordset("Emp_Table")
Open "Testdata.dat" For Input As #1
BeginTrans
Do While Not (EOF(1))
newtb.AddNew
Line Input #1, tmp1$ 'Retrieve empl_id
Line Input #1, tmp2$ 'Retrieve empl_name
Line Input #1, tmp3$ 'Retrieve empl_addr
Line Input #1, tmp4$
newtb("Emp_ID") = Trim$(tmp1$) 'Place in field1
newtb("Emp_Name") = Trim$(tmp2$) 'Place in field2
newtb("Emp_Addr") = Trim$(tmp3$) 'Place in field3
newtb("Emp_SSN") = Trim$(tmp4$) 'Place in field4
newtb.Update 'Save to table
Loop
CommitTrans
Close #1 'Close text file
newtb.Close 'Close DB's table
newdb.Close 'Close DB
screen.MousePointer = 0 'Set back to show done
End Sub
在Command3_Click事件中加入下面的代码
Sub Command3_Click ()
Dim db As Database
Dim t As Recordset
Dim counter%
Set db = OpenDatabase("NEWDB.MDB")
Set t = db.OpenRecordset("Emp_Table")
counter% = 1 'Start counter at Row=1
Do Until t.EOF
grid2.Col = 1
grid2.Row = counter%
grid2.Text = t(0) 'Load Emp ID
grid2.Col = 2
grid2.Row = counter%
grid2.Text = t(1) 'Load Emp Name
grid2.Col = 3
grid2.Row = counter%
grid2.Text = t(2) 'Load Emp Addr
grid2.Col = 4
grid2.Row = counter%
grid2.Text = t(3) 'Load Emp SSN
counter% = counter% + 1
t.MoveNext
Loop
t.Close
db.Close
End Sub
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