在VB6中用Select语句检索记录

　　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