SQL2005 如何判断某列是否为外键

select 
  oSub.name  AS  [子表名称],
  fk.name AS  [外键名称],
  SubCol.name AS [子表列名],
  oMain.name  AS  [主表名称],
  MainCol.name AS [主表列名]
from 
  sys.foreign_keys fk  
    JOIN sys.all_objects oSub  
        ON (fk.parent_object_id = oSub.object_id)
    JOIN sys.all_objects oMain 
        ON (fk.referenced_object_id = oMain.object_id)
    JOIN sys.foreign_key_columns fkCols 
        ON (fk.object_id = fkCols.constraint_object_id)
    JOIN sys.columns SubCol 
        ON (oSub.object_id = SubCol.object_id  
            AND fkCols.parent_column_id = SubCol.column_id)
    JOIN sys.columns MainCol 
        ON (oMain.object_id = MainCol.object_id  
            AND fkCols.referenced_column_id = MainCol.column_id)
WHERE
  oSub.name  =  '你的表名字'
  AND  SubCol.name  =  '你的列名'