AdoDB.recordcount的小问题？

zhsunson 2004-09-28 01:03:42

AdoDB.recordcount的小问题？
返回数据集时，有时正常，有时为-1。
我要得到数据集的记录数，为-1时如何处理？

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bladeinside 2004-09-28

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我们常用RecordCount属性来找出一个Recordset对象包括多少条记录。使用 RecordCount 属性可确定Recordset 对象中记录的数目。ADO 无法确定记录数时，或者如果提供者或游标类型不支持 RecordCount，则该属性返回 –1。读已关闭的 Recordset 上的 RecordCount 属性将产生错误。Recordset 对象的游标类型会影响是否能够确定记录的数目。对仅向前游标，RecordCount 属性将返回 -1，对静态或键集游标返回实际计数，对动态游标取决于数据源返回 -1 或实际计数。

或者
由于默认的记录集游标是服务器游标，
Rs.CursorLocation = adUseServer
所以返回Rs.RecordCount=-1,
应该把服务器游标改为客户端游标，
Rs.CursorLocation = adUseClient

ryuginka 2004-09-28

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还有一种方法,就是在打开之前
加上
rs.movelast
rs.movefirst

huangjing81 2004-09-28

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改游标

vzxq 2004-09-28

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把游标类型改一下就成，改为静态的

chelseawu 2004-09-28

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Dim DB As New ADODB.Connection
Dim rs As New ADODB.Recordset
Private Const connstr = "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog= ;Data Source= "

Private Sub Form_Load()
DB.ConnectionTimeout = 0
DB.CursorLocation = adUseClient
DB.OPEN connstr
End Sub

chelseawu 2004-09-28

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Dim conn As New ADODB.Connection
Dim rs As New ADODB.Recordset

Private Sub Form_Load()
DB.ConnectionTimeout = 0
DB.CursorLocation = adUseClient
End Sub

jam021 2004-09-28

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VB ADODB SQL 精确查找并排序、模糊查询并排序、随机提取多条记录、统计记录总数（精确查找并排序、模糊查询并排序、随机提取多条记录、统计记录总数）

SQL+VB做成的licit Public gUserName As String Public gUserKind As String Public gEmployeeId As String Public gLoginSucceeded As Boolean Public Const BLUE = &HFF0000 Public Const WHITE = &H80000005 Sub Main() Dim fLogin As New frmLogin '启动登录窗体 fLogin.Show vbModal '装入并显示模式窗体。 If Not gLoginSucceeded Then MsgBox "系统启动失败,请重试!", vbOKOnly + vbExclamation, "警告" End If Unload fLogin End Sub Public Function ConnectString() As String ConnectString = "Provider=SQLOLEDB.1;Password=sa;User ID=sa;Initial Catalog=DBManPower;Data Source=127.0.0.1;" End Function Public Function ExecuteSQL(ByVal SQL As String, rst As ADODB.Recordset, _ Optional enableWrite As Boolean = True) As Boolean Dim con As ADODB.Connection Dim sTokens() As String On Error GoTo Execute_Error sTokens = Split(SQL) Set con = New ADODB.Connection con.Open ConnectString '打开数据库 Set rst = New ADODB.Recordset If enableWrite Then '读写方式 rst.Open Trim$(SQL), con, adOpenStatic, adLockOptimistic Else '只读方式 rst.Open Trim$(SQL), con, adOpenStatic, adLockReadOnly End If ExecuteSQL = True Exit Function Execute_Error: ExecuteSQL = False Exit Function End Function Public Function DBExist(ByVal SQL As String) As Integer Dim con As ADODB.Connection Dim sTokens() As String Dim flag As String Dim rst As ADODB.Recordset sTokens = Split(SQL) Set con = New ADODB.Connection con.Open ConnectString flag = ExecuteSQL(SQL, rst, False) '判断该记录是否存在 If rst.RecordCount <> 0 Then DBExist = rst.RecordCount Else DBExist = 0 End If con.Close End Function Public Function txtIsNull(txt As TextBox) As Boolean If Trim(txt.Text) = "" Then txtIsNull = True txt.SetFocus txt.BackColor = BLUE Else txtIsNull = False End If

部分源代码： Private Sub Command1_Click() Dim sql As String Dim param As ADODB.Parameter Dim cmd As ADODB.Command Set cmd = New ADODB.Command Set param = New ADODB.Parameter sql = "select * from book where [图书编码]= ? " If Command1.Caption = "添加记录" Then Command1.Caption = "确定" Command2.Enabled = False '屏蔽删除、修改、下一记录、上一记录按钮，避免出现数据库错误 Command3.Enabled = False Command4.Enabled = False cmdmodify.Enabled = False rst.AddNew Else If Text1.Text = "" Then frmMsg.Show frmMsg.notice.Visible = True frmMsg.Text1.Text = "图书编号不能为空!" Command2.Enabled = True Command3.Enabled = True Command4.Enabled = True Command1.Caption = "添加记录" Exit Sub End If With param .Direction = adParamInput .Type = adBSTR .Size = 8 .Value = Text1.Text End With cmd.Parameters.Append param cmd.CommandText = sql cmd.CommandType = adCmdText Set cmd.ActiveConnection = con Set rst1 = cmd.Execute If rst1.RecordCount > 0 Then frmMsg.Show frmMsg.notice.Visible = True frmMsg.Text1.Text = "此书号已经存在!" rst.Cancel Command2.Enabled = True Command3.Enabled = True Command4.Enabled = True cmdmodify.Enabled = True Command1.Caption = "添加记录" Command2.Enabled = True Exit Sub End If rst.Update Command2.Enabled = True '数据库更新结束后才可以点击其他几个按钮 Command3.Enabled = True Command4.Enabled = True cmdmodify.Enabled = True Command1.Caption = "添加记录" End If End Sub 修改图书记录操作 Private Sub cmdmodify_Click() '修改记录按钮 Dim sqlstr As String Dim rst1 As New ADODB.Recordset Dim param As ADODB.Parameter Dim cmd As ADODB.Command Set cmd = New ADODB.Command Set param = New ADODB.Parameter sqlstr = "select * from book where [图书编码]= '" & Trim(Text1.Text) & "'" With param .Direction = adParamInput .Type = adBSTR .Size = 8 .Value = Text1.Text End With cmd.Parameters.Append param cmd.CommandText = sqlstr cmd.CommandType = adCmdText Set cmd.ActiveConnection = con Set rst1 = cmd.Execute If rst1.RecordCount > 0 Then frmMsg.Show frmMsg.notice.Visible = True frmMsg.Text1.Text = "此书号已经存在!" rst.Cancel Exit Sub End If rst.Update frmMsg.Show frmMsg.info.Visible = True frmMsg.Text1.Text = "修改成功!" End Sub 添加职工信息 Private Sub Command1_Click() '添加记录 Dim sql As String Dim param As ADODB.Parameter Dim cmd As ADODB.Command Set cmd = New ADODB.Command Set param = New ADODB.Parameter sql = "select * from worker where [工号]= ? " If Command1.Caption = "添加记录" Then Command1.Caption = "确定" Command2.Enabled = False Command3.Enabled = False Command4.Enabled = False rst.AddNew Else If Text1.Text = "" Then frmMsg.Show frmMsg.notice.Visible = True frmMsg.Text1.Text = "职工编号不能为空!" Command2.Enabled = True Command3.Enabled = True Command4.Enabled = True Command1.Caption = "添加记录" Exit Sub End If With param .Direction = adParamInput .Type = adBSTR .Size = 8 .Value = Text1.Text End With cmd.Parameters.Append param cmd.CommandText = sql cmd.CommandType = adCmdText Set cmd.ActiveConnection = con Set rst1 = cmd.Execute '检测职工编号是否存在防止主键冲突 If rst1.RecordCount > 0 Then frmMsg.Show frmMsg.notice.Visible = True frmMsg.Text1.Text = "此职工编号已经存在!" rst.Cancel Command2.Enabled = True Command3.Enabled = True Command4.Enabled = True Command1.Caption = "添加记录" Exit Sub End If rst.Update Command2.Enabled = True Command3.Enabled = True Command4.Enabled = True Command1.Caption = "添加记录" End If End Sub

vb学生管理系统源代码部分代码 Public UserName As String Public txtSQL As String 'use to store record SQLsentence Public dream As ADODB.Recordset 'use to store record object Public Msgtext As String '用来存放返回信息 Public OK As Boolean ' 'Public db As String Public Sub highlight() With Screen.ActiveForm If (TypeOf .ActiveControl Is TextBox) Then .ActiveControl.SelStart = 0 .ActiveControl.SelLength = Len(.ActiveControl) End If End With End Sub Sub Main() 'Dim Login As New Login 'Login.Show vbModal 'f Not Login.OK Then 'Login Failed so exit app ' End 'End If 'Unload studentmdi ' Set login = New login login.Show End Sub Public Function connectstring() As String connectstring = "Provider=Microsoft.jet.OLEDB.3.51;Data source=f:\schoolgroup\school.mdb" End Function Public Function ExecuteSQL(ByVal SQL As String, Msgstring As String) As ADODB.Recordset Dim cnn As ADODB.Connection Dim rst As ADODB.Recordset Dim sTokens() As String On Error GoTo ExecuteSQL_Error sTokens = Split(SQL) Set cnn = New ADODB.Connection cnn.Open connectstring If InStr("INSERT,DELETE,UPDATE", UCase$(sTokens(0))) Then cnn.ExecuteSQL Msgstring = sTokens(0) & "query successful" Else Set rst = New ADODB.Recordset rst.Open Trim(SQL), cnn, adOpenKeyset, adLockOptimistic Set ExecuteSQL = rst Msgstring = "查询到" & rst.RecordCount & " 条记录" End If executeSQL_exit: Set rst = Nothing Set cnn = Nothing Exit Function ExecuteSQL_Error: Msgstring = "查询错误：" & err.Description Resume executeSQL_exit End Function Public Function Testtxt(txt As String) As Boolean If Trim(txt) = "" Then Testtxt = False Else Testtxt = True End If End Function

VB中recordset的用法，很全，很不错

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