在vb中的处理方法 本程序也可以用oo4o实现下面这段程序将一个文件(文本文件,doc文件,图象文件等)保存到数据库中,并可以将其从数据库读出。需要两个commandbutton cmd1 名称 cmdsave caption 保存 cmd2 名称 cmdread caption 读取 一个cmddialog控件Option Explicit Dim rn As ADODB.ConnectionPublic Function CreateDataSource(DataSource As String, UserID As String, Password As String) As Boolean On Error GoTo DbConErr: Set rn = New ADODB.Connection With rn .ConnectionString = "Provider=OraOledb.Oracle.1;" & _ "password=" & Password & ";" & _ "User ID =" & UserID & ";" & _ "Data Source=" & DataSource & ";" & _ "Locale Identifier=2052" .Open End With CreateDataSource = True Exit Function DbConErr: CreateDataSource = False End FunctionPrivate Sub cmdRead_Click() Dim rs As New ADODB.Recordset rs.ActiveConnection = rn rs.LockType = adLockOptimistic rs.CursorLocation = adUseClient rs.Source = "select * from t_demo" rs.Open ComDlgDir.DialogTitle = "保存文件" ComDlgDir.Filter = "*.*" ComDlgDir.ShowSave Call BlobToFile(rs.Fields("text"), ComDlgDir.filename) Set rs = Nothing Exit Sub Set rs = Nothing End SubPrivate Sub cmdsave_Click() Dim rs As New ADODB.Recordset rs.ActiveConnection = rn rs.LockType = adLockOptimistic rs.CursorLocation = adUseClient rs.Source = "select * from t_demo" rs.Open rs.AddNew ComDlgDir.DialogTitle = "选取文件" ComDlgDir.ShowOpen rs.Fields("id").Value = 1 If ComDlgDir.filename <> "" Then Call FileToBlob(rs.Fields("text"), ComDlgDir.filename) rs.Update End If Set rs = Nothing Exit Sub Set rs = Nothing End SubPrivate Sub Form_Load() If Not CreateDataSource("sid", "systemp", "manager") Then MsgBox "Connection failure!" End If End SubSub FileToBlob(ByRef fld As ADODB.Field, filename As String, Optional ChunkSize As Long = 8192) Dim fnum As Integer, bytesleft As Long, bytes As Long Dim tmp() As Byte If (fld.Attributes And adFldLong) = 0 Then Err.Raise 1001, , "field doesn't support the GetChunk method." End If If Dir$(filename) = "" Then Err.Raise 53, , "File not found" fnum = FreeFile Open filename For Binary As fnum bytesleft = LOF(fnum) Do While bytesleft bytes = bytesleft If bytes > ChunkSize Then bytes = ChunkSize ReDim tmp(1 To bytes) As Byte Get fnum, , tmp fld.AppendChunk tmp bytesleft = bytesleft - bytes Loop Close #fnum End SubSub BlobToFile(fld As ADODB.Field, filename As String, Optional ChunkSize As Long = 8192) Dim fnum As Integer, bytesleft As Long, bytes As Long Dim tmp() As Byte If (fld.Attributes And adFldLong) = 0 Then Err.Raise 1001, , "field doesn't support the GetChunk method." End If If Dir$(filename) <> "" Then Kill filename fnum = FreeFile Open filename For Binary As fnum bytesleft = fld.ActualSize Do While bytesleft bytes = bytesleft If bytes > ChunkSize Then bytes = ChunkSize tmp = fld.GetChunk(bytes) Put #fnum, , tmp bytesleft = bytesleft - bytes Loop Close #fnum End Sub
本程序也可以用oo4o实现下面这段程序将一个文件(文本文件,doc文件,图象文件等)保存到数据库中,并可以将其从数据库读出。需要两个commandbutton
cmd1 名称 cmdsave caption 保存
cmd2 名称 cmdread caption 读取
一个cmddialog控件Option Explicit
Dim rn As ADODB.ConnectionPublic Function CreateDataSource(DataSource As String, UserID As String, Password As String) As Boolean
On Error GoTo DbConErr:
Set rn = New ADODB.Connection
With rn
.ConnectionString = "Provider=OraOledb.Oracle.1;" & _
"password=" & Password & ";" & _
"User ID =" & UserID & ";" & _
"Data Source=" & DataSource & ";" & _
"Locale Identifier=2052"
.Open
End With
CreateDataSource = True
Exit Function
DbConErr:
CreateDataSource = False
End FunctionPrivate Sub cmdRead_Click()
Dim rs As New ADODB.Recordset
rs.ActiveConnection = rn
rs.LockType = adLockOptimistic
rs.CursorLocation = adUseClient
rs.Source = "select * from t_demo"
rs.Open
ComDlgDir.DialogTitle = "保存文件"
ComDlgDir.Filter = "*.*"
ComDlgDir.ShowSave
Call BlobToFile(rs.Fields("text"), ComDlgDir.filename)
Set rs = Nothing
Exit Sub
Set rs = Nothing
End SubPrivate Sub cmdsave_Click()
Dim rs As New ADODB.Recordset
rs.ActiveConnection = rn
rs.LockType = adLockOptimistic
rs.CursorLocation = adUseClient
rs.Source = "select * from t_demo"
rs.Open
rs.AddNew
ComDlgDir.DialogTitle = "选取文件"
ComDlgDir.ShowOpen
rs.Fields("id").Value = 1
If ComDlgDir.filename <> "" Then
Call FileToBlob(rs.Fields("text"), ComDlgDir.filename)
rs.Update
End If
Set rs = Nothing
Exit Sub
Set rs = Nothing
End SubPrivate Sub Form_Load()
If Not CreateDataSource("sid", "systemp", "manager") Then
MsgBox "Connection failure!"
End If
End SubSub FileToBlob(ByRef fld As ADODB.Field, filename As String, Optional ChunkSize As Long = 8192)
Dim fnum As Integer, bytesleft As Long, bytes As Long
Dim tmp() As Byte
If (fld.Attributes And adFldLong) = 0 Then
Err.Raise 1001, , "field doesn't support the GetChunk method."
End If
If Dir$(filename) = "" Then Err.Raise 53, , "File not found"
fnum = FreeFile
Open filename For Binary As fnum
bytesleft = LOF(fnum)
Do While bytesleft
bytes = bytesleft
If bytes > ChunkSize Then bytes = ChunkSize
ReDim tmp(1 To bytes) As Byte
Get fnum, , tmp
fld.AppendChunk tmp
bytesleft = bytesleft - bytes
Loop
Close #fnum
End SubSub BlobToFile(fld As ADODB.Field, filename As String, Optional ChunkSize As Long = 8192)
Dim fnum As Integer, bytesleft As Long, bytes As Long
Dim tmp() As Byte
If (fld.Attributes And adFldLong) = 0 Then
Err.Raise 1001, , "field doesn't support the GetChunk method."
End If
If Dir$(filename) <> "" Then Kill filename
fnum = FreeFile
Open filename For Binary As fnum
bytesleft = fld.ActualSize
Do While bytesleft
bytes = bytesleft
If bytes > ChunkSize Then bytes = ChunkSize
tmp = fld.GetChunk(bytes)
Put #fnum, , tmp
bytesleft = bytesleft - bytes
Loop
Close #fnum
End Sub
在Oracle里用BLOB,CLOB,NCLOB有什么区别吗.
哪个更快,哪个更小.哪个读取效率更高