DatabaseQuery Class
A class for specifying additional parameters to DatabaseDataSet queries.
NuGet/Assembly: Carmenta.Engine.5.16.2.nupkg (in the CEDataSets assembly)
Syntax
public class DatabaseQuery : QueryRemarks
This class extends the Query class with database-specific query parameters. It can be used together with an DatabaseDataSet, to limit queries to only read one or more specific feature types from a database.
When specifying the Filter or the SelectStatement you can use a special syntax to include some predefined attributes and update attributes (see View.UpdateAttributes) in the query. To use the attributes as bind variables/parameters prefix them with $ instead of :.
The available predefined attributes are listed in the table below.
AttributeName | Description |
|---|---|
:tableName | The name of the database table name specified in the table property of the DatabaseDataSet. |
:keyColumn | The name of the database column used as the key specified in the keyColumn property or detected by the DatabaseDataSet. |
:attributeList | The names of the database columns that are specified in the attributes property or detected by the DatabaseDataSet. |
:geometryColumn | The name of the database column that contains the geometry specified in the geometryColumn property or detected by the DatabaseDataSet . |
:sridString | The value of the srid property specified in or detected by the DatabaseDataSet. |
:wktArea | The current view area as a polygon in well-known text (WKT) format. |
:xMin | The x-coordinate of the left edge of the current view area. |
:yMin | The y-coordinate of the bottom edge of the current view area. |
:xMax | The x-coordinate of the right edge of the current view area. |
:yMax | The y-coordinate of the top edge of the current view area. |
for usage examples see SelectStatement.
Inheritance Hierarchy
System.Object (not available in C#)
EngineObject
ResourceObject
Query
DatabaseQuery
Platforms
Windows, Linux, Android
DatabaseQuery Members
The DatabaseQuery type has the following members.
Constructors
| Name | Description |
|---|---|
| DatabaseQuery | Initializes a new instance of the DatabaseQuery class |
Properties
| Name | Description |
|---|---|
| Filter | Gets or sets a filter condition. |
| IsDisposed | Gets a value that tells whether the current DatabaseQuery has been disposed. Inherited from EngineObject |
| Name | Gets or sets the name of the DatabaseQuery. Inherited from ResourceObject |
| NativeHandle | Gets the native Carmenta Engine kernel object the current DatabaseQuery represents. Inherited from EngineObject |
| ReadLines | Gets or sets a flag indicating if line features should be read from the dataset. Inherited from Query |
| ReadMeshes | Gets or sets a flag indicating if mesh features should be read from the dataset. Inherited from Query |
| ReadMultiGeometries | Gets or sets a flag indicating if multi-geometry features should be read from the dataset. Inherited from Query |
| ReadMultiLines | Gets or sets a flag indicating if multi-line features should be read from the dataset. Inherited from Query |
| ReadMultiPoints | Gets or sets a flag indicating if multi-point features should be read from the dataset. Inherited from Query |
| ReadMultiPolygons | Gets or sets a flag indicating if multi-polygon features should be read from the dataset. Inherited from Query |
| ReadPoints | Gets or sets a flag indicating if point features should be read from the dataset. Inherited from Query |
| ReadPolygons | Gets or sets a flag indicating if polygon features should be read from the dataset. Inherited from Query |
| ReadRasters | Gets or sets a flag indicating if raster features should be read from the dataset. Inherited from Query |
| ResolutionFactor | Gets or sets a value that adjusts the resolution a ReadOperator requests when it reads data from a DataSet. Inherited from Query |
| SelectStatement | Gets or sets a SQL SELECT statement. |
| IUserProperties.UserProperties | Gets the AttributeSet that contains the user properties. Inherited from IUserProperties |
Methods
| Name | Description |
|---|---|
| Clone | Creates a copy of an object. Inherited from EngineObject |
| Dispose | Releases the reference to the native Carmenta Engine kernel instance the EngineObject represents. Inherited from EngineObject |
| Equals | Determines whether this instance is equal to another. Inherited from EngineObject |
| Match | Checks if a Feature matches the Query. Inherited from Query |