如何用ADO SQL2000存取二进制型数据varbinary 和 image型数据?(100)

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々飞翔鸟々

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• 2009-03-14

• #1

如何用ADO SQL2000存取二进制型数据varbinary 和 image型数据?希望能提供一份例子，谢谢

 

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zkktom

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• 2009-03-14

• #2

if (adods.RecordCount > 0) then begin adods.First; bField := TBlobField(adods.FieldByName('nr')); bField.SaveToStream(result); end; 读取 if anr.Size>0 then ParamByName('name1').LoadFromStream(anr, ftBlob);、、保存

 

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znxia

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• 2009-03-14

• #3

TBlobField(adods.FieldByName('nr')).savetofile ( filename )TBlobField(adods.FieldByName('nr')).loadfromfile ( filename )

 

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々飞翔鸟々

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• 2009-03-16

• #4

给完整点好吗？

 

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znxia

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• 2009-03-16

• #5

是你的要求不够具体。ADOQuery.Close;ADOQuery.SQL.TEXT:='Select * From 表1';ADOQuery.Open;这样就取得数据了啊，关键是你下一步想干嘛？

 

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々飞翔鸟々

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• 2009-03-16

• #6

我想读出来， 放到一个char buf[]中， 应该怎么做？谢谢我用下面的代码写进数据库去了 int countofchar = 100; unsigned char data[100]; for (int i = 0; i < countofchar; i++) { data = (unsigned char) i; } VARIANT varBLOB; SAFEARRAY *psa; SAFEARRAYBOUND rgsabound[1]; rgsabound[0].lLbound = 0; rgsabound[0].cElements = countofchar; psa = SafeArrayCreate(VT_UI1, 1, rgsabound); BYTE* pByte; if(SafeArrayAccessData(psa,(void**)&pByte) == NOERROR) memcpy((LPVOID)pByte,(LPVOID)&data, countofchar); SafeArrayUnaccessData(psa); varBLOB.vt = VT_ARRAY | VT_UI1; varBLOB.parray = psa; Q->Close(); Q->SQL->Clear(); Q->SQL->Text = "select * from abc"; Q->Open(); Q->Append(); Q->FieldByName("test")->AsVariant = varBLOB; Q->Post();现在我想读出来， 放到一个char buf[]中， 应该怎么做？谢谢

 

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znxia

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• 2009-03-16

• #7

Stream:= TMemoryStream.Create; TBlobField( Q.FieldByName(test') ).SaveToStream( Stream ); Stream.Position:=0; Stream.Read( Buffer, Stream.Size ) Stream.FREE;

 

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々飞翔鸟々

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• 2009-03-16

• #8

执行到这句 TBlobField( Q.FieldByName(test') ).SaveToStream( Stream );时出错：Invalid class typecast编译没问题

 

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々飞翔鸟々

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• 2009-03-16

• #9

刚才把数据类型从varbinary 改成 image 就不报Invalid class typecast错了 不知道为啥

 

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znxia

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• 2009-03-16

• #10

if Q.FieldByName(test').IsBlob thenbegin Stream:= TMemoryStream.Create; TBlobField( Q.FieldByName(test') ).SaveToStream( Stream ); Stream.Position:=0; Stream.Read( Buffer, Stream.Size ) Stream.FREE; endelse showmessage('字段不是Blob类型的');-------------或者你读到一个variant类型里面去，然后在逐个读取出来。

 

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々飞翔鸟々

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• 2009-03-16

• #11

谢谢

 

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々飞翔鸟々

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• 2009-03-16

• #12

接受答案了.