用ORACLE数据库存储海量图像数据

buffer = String$(chunksize, 32)
FNum = FreeFile
'打开文件 
Open "partdesc.dat" For Binary As #FNum
'设置offset和PollingAmount属性 
'写入操作 
PartDesc.offset = 1
PartDesc.PollingAmount = LOF(FNum)
remainder = LOF(FNum)
'锁定写入行 
OraDynaset.Edit
Get #FNum, , buffer
'第一次写入操作 
amount_written = PartDesc.Write(buffer, chunksize, ORALOB_FIRST_PIECE)
While PartDesc.Status = ORALOB_NEED_DATA
remainder = remainder - chunksize
If remainder < chunksize Then
piecetype = ORALOB_LAST_PIECE
chunksize = remainder
Else
piecetype = ORALOB_NEXT_PIECE
End If
Get #FNum, , buffer
amount_written = PartDesc.Write(buffer, chunksize, piecetype)
Wend
Close FNum
'更新提交 
OraDynaset.Update
从数据库中读取数据：
Dim OraSession As OraSession
Dim OraDatabase As OraDatabase
Dim OraDynaset As OraDynaset
Dim PartImage As OraBlob
Dim chunksize As Long
Dim AmountRead As Long
Dim buffer As Variant
Dim buf() As Byte
'建立 OraSession对象 
Set OraSession = CreateObject("OracleInProcServer.XOraSession")
'建立OraDatabase对象 
Set OraDatabase = OraSession.OpenDatabase("ExampleDb","scott/tiger", 0&)
'建立OraDynaset对象 
Set OraDynaset = OraDatabase.CreateDynaset("select * from part", 0&)
'从动态集中获得OraBlob 
Set PartImage = OraDynaset.Fields("part_image").Value
'设置Offset和PollingAmount属性 

PartImage.offset = 1
PartImage.PollingAmount = PartImage.Size
chunksize = 50000
'获得自由文件号 

FNum = FreeFile
'打开文件 
Open "image.dat" For Binary As #FNum
'第一次读 
AmountRead = PartImage.Read(buffer, chunksize)
buf = buffer
Put #FNum, , buf
' 检查属性 
While PartImage.Status = ORALOB_NEED_DATA
AmountRead = PartImage.Read(buffer, chunksize)
buf = buffer
Put #FNum, , buf
Wend
Close FNum