blob类型数据输入的问题(100)

用下列语句输入blob类型数据： with SQLStoredProc1.Params.CreateParam(ftblob, 'tuxiang', ptInput) do Asblob:=opendialog1;编译通不过，显示如下：[Error] Unit1.pas(114): Incompatible types: 'String' and 'TOpenDialog'[Fatal Error] Project1.dpr(5): Could not compile used unit 'Unit1.pas'

Asblob:=opendialog1; asbolb := opendialog1.filename;