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从oracle spatial读取几何字段的坐标值:
有如下一些方式:
1.使用oci或者occi,在安装oracle后可以在oraclehome\md\demo\examples目录下参考其C++实现,
该方法效率最高,但实现比较复杂;
2.使用Oracle提供的OO4O,是com,在vb6代码如下:
'***************************************************************
'Gisc Lab, Nanjing Normal University
'
' urpose: This Demo Shows how to read spatial data from Oracle
'
'Input: User ID='Scott', Password='Tiger', Data Source='Apollo',
' SQL='select * from interstates where rownum<2'
'
'Output: xmlDocument or xmlReader
'
'Author: Charlie Chen
'
'Data: 7-28-2004
'***************************************************************
Dim OraSession As OraSessionClass
Dim OraDatabase As OraDatabase
Dim interstates As OraDynaset
Dim geom As OraObject
Dim coords As OraCollection
Private Sub Command1_Click()
Set OraSession = New OraSessionClass
Set OraDatabase = OraSession.OpenDatabase("apollo", "scott/tiger", 0&)
Set interstates = OraDatabase.CreateDynaset("select * from interstates where rownum<2", 0&)
Set geom = interstates.Fields("GEOM").Value
Set coords = geom.SDO_ORDINATES
For i = 1 To coords.Size
Debug.Print coords.Item(i)
Next i
End Sub
程序可读性和维护性较好,需要添加对oip9.tlb的引用
3.使用ODP.NET(Oracle公司提供的在.net平台上的数据访问组件),在.NET环境下可以直接转换为xml坐标字符串,但效率太低;
4.使用JDBC或者SDO API,无论从哪方面来讲都比较理想。 |
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