SpatialEdmFunctions.Elevation(DbExpression) 方法
定义
创建 DbFunctionExpression,它使用指定参数(该参数必须具有 Edm.Geography 或 Edm.Geometry 结果类型)调用规范 'Elevation' 函数。Creates a DbFunctionExpression that invokes the canonical 'Elevation' function with the specified argument, which must have an Edm.Geography or Edm.Geometry result type. 该表达式的结果类型为 Edm.Double。The result type of the expression is Edm.Double.
public:
[System::Runtime::CompilerServices::Extension]
static System::Data::Common::CommandTrees::DbFunctionExpression ^ Elevation(System::Data::Common::CommandTrees::DbExpression ^ spatialValue);
public static System.Data.Common.CommandTrees.DbFunctionExpression Elevation (this System.Data.Common.CommandTrees.DbExpression spatialValue);
static member Elevation : System.Data.Common.CommandTrees.DbExpression -> System.Data.Common.CommandTrees.DbFunctionExpression
<Extension()>
Public Function Elevation (spatialValue As DbExpression) As DbFunctionExpression
参数
- spatialValue
- DbExpression
一个表达式,从应检索的提升(Z 坐标)值中指定空间点的值。An expression that specifies the spatial point value from which the elevation (Z co-ordinate) value should be retrieved.
返回
一个新的 DbFunctionExpression,它返回 spatialValue 的提升值或返回 null(如果 spatialValue 不是点)。A new DbFunctionExpression that returns either the elevation value of spatialValue or null if spatialValue is not a point.
例外
spatialValue
spatialValue