form1.frm

从数据库抽取数据

VERSION 5.00
Object = "{02B5E320-7292-11CF-93D5-0020AF99504A}#1.0#0"; "MSCHART.OCX"
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   5040
   ClientLeft      =   1095
   ClientTop       =   825
   ClientWidth     =   7200
   LinkTopic       =   "Form1"
   PaletteMode     =   1  'UseZOrder
   ScaleHeight     =   5040
   ScaleWidth      =   7200
   Begin MSChartLib.MSChart Chart1 
      Height          =   4815
      Left            =   120
      OleObjectBlob   =   "Form1.frx":0000
      TabIndex        =   0
      Top             =   120
      Width           =   6975
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit

Private Values() As Single
Private NumPoints As Integer

Private Sub LoadData()
Dim db As Database
Dim qdef As QueryDef
Dim rs As Recordset
Dim dbname As String
Dim i As Integer

    ' Open the database.
    dbname = App.Path
    If Right$(dbname, 1) <> "\" Then dbname = dbname & "\"
    dbname = dbname & "data.mdb"
    Set db = OpenDatabase(dbname)

    ' Get the records.
    Set qdef = db.CreateQueryDef("", _
        "SELECT Year, Value FROM YearlyValues")
    Set rs = qdef.OpenRecordset(dbOpenSnapshot)
    
    ' See how many records there are.
    rs.MoveLast
    NumPoints = rs.RecordCount
    ReDim Values(1 To NumPoints, 1 To 2)

    ' Load the data.
    rs.MoveFirst
    For i = 1 To NumPoints
        Values(i, 1) = Format$(rs!Year, "yyyy")
        Values(i, 2) = rs!Value
        rs.MoveNext
    Next i

    rs.Close
    db.Close
End Sub
Private Sub MakeData()
Const NUM_POINTS = 40
Dim db As Database
Dim dbname As String
Dim i As Integer
Dim the_year As Date
Dim the_value As Single
Dim sql As String

    ' Open the database.
    dbname = App.Path
    If Right$(dbname, 1) <> "\" Then dbname = dbname & "\"
    dbname = dbname & "data.mdb"
    Set db = OpenDatabase(dbname)

    ' Delete any old data.
    sql = "DELETE FROM YearlyValues"
    db.Execute sql
    
    ' Create a bunch of data.
    the_year = #1/1/60#
    the_value = 1000
    For i = 1 To 38
        sql = "INSERT INTO YearlyValues VALUES (#" & _
            Format$(the_year) & "#, " & _
            Format$(the_value) & ")"
        db.Execute sql
        
        the_year = DateAdd("yyyy", 1, the_year)
        the_value = the_value + Rnd * 2
    Next i

    db.Close
End Sub

Private Sub Form_Load()
Const MAKING_DATA = False

    If MAKING_DATA Then
        MakeData
        Unload Me
    Else
        LoadData
    
        ' Send the data to the chart.
        Chart1.chartType = VtChChartType2dXY
        Chart1.RowCount = NumPoints
        Chart1.ColumnCount = 2
        Chart1.ChartData = Values
    End If
End Sub