Introduced new GetTopicUpdates stored procedure

This retrieves any updates to the database—including new or modified `Topics`, `Attributes`, `ExtendedAttributes`, `Relationships`, or `TopicReferences`—since a given date, assuming that date is within the last twenty four hours.

OnTopic.Data.Sql.Database/OnTopic.Data.Sql.Database.sqlproj

@@ -127,6 +127,7 @@
     <Build Include="Stored Procedures\UpdateExtendedAttributes.sql" />
     <Build Include="Views\ReferenceIndex.sql" />
     <Build Include="Views\RelationshipIndex.sql" />
+    <Build Include="Stored Procedures\GetTopicUpdates.sql" />
   </ItemGroup>
   <ItemGroup>
     <ArtifactReference Include="$(DacPacRootPath)\Extensions\Microsoft\SQLDB\Extensions\SqlServer\130\SqlSchemas\master.dacpac">

OnTopic.Data.Sql.Database/Stored Procedures/GetTopicUpdates.sql

@@ -0,0 +1,121 @@
+--------------------------------------------------------------------------------------------------------------------------------
+-- GET TOPIC UPDATES
+--------------------------------------------------------------------------------------------------------------------------------
+-- Retrieves any data persisted to the database since the last query.
+--------------------------------------------------------------------------------------------------------------------------------
+
+CREATE PROCEDURE [dbo].[GetTopicUpdates]
+	@Since		DATETIME
+AS
+
+--------------------------------------------------------------------------------------------------------------------------------
+-- SELECT KEY ATTRIBUTES
+--------------------------------------------------------------------------------------------------------------------------------
+SELECT	TopicID,
+  	ContentType,
+  	ParentID,
+  	TopicKey,
+  	0 AS SortOrder
+FROM	Topics
+WHERE	LastModified		> @Since
+
+--------------------------------------------------------------------------------------------------------------------------------
+-- SELECT TOPIC ATTRIBUTES
+--------------------------------------------------------------------------------------------------------------------------------
+;WITH	TopicAttributes
+AS (
+  SELECT	TopicID,
+	AttributeKey,
+	AttributeValue,
+	Version,
+	RowNumber		= ROW_NUMBER() OVER (
+	  PARTITION BY		TopicID,
+			AttributeKey
+	  ORDER BY		Version		DESC
+	)
+  FROM	Attributes
+  WHERE	Version		> @Since
+)
+SELECT	TopicID,
+	AttributeKey,
+	AttributeValue,
+	Version
+FROM	TopicAttributes
+WHERE	RowNumber		= 1
+
+--------------------------------------------------------------------------------------------------------------------------------
+-- SELECT EXTENDED ATTRIBUTES
+--------------------------------------------------------------------------------------------------------------------------------
+;WITH	TopicExtendedAttributes
+AS (
+  SELECT	TopicID,
+	AttributesXml,
+	Version,
+	RowNumber		= ROW_NUMBER() OVER (
+	  PARTITION BY		TopicID
+	  ORDER BY		Version		DESC
+	)
+  FROM	ExtendedAttributes
+  WHERE	Version		> @Since
+)
+SELECT	TopicID,
+	AttributesXml,
+	Version
+FROM	TopicExtendedAttributes
+WHERE	RowNumber		= 1
+
+--------------------------------------------------------------------------------------------------------------------------------
+-- SELECT RELATIONSHIPS
+--------------------------------------------------------------------------------------------------------------------------------
+;WITH Relationships AS (
+  SELECT	Source_TopicID,
+	RelationshipKey,
+	Target_TopicID,
+	IsDeleted,
+	Version,
+	RowNumber = ROW_NUMBER() OVER (
+	  PARTITION BY		Source_TopicID,
+			RelationshipKey
+	  ORDER BY		Version	DESC
+	)
+  FROM	[dbo].[Relationships]
+  WHERE	Version		> @Since
+)
+SELECT	Relationships.Source_TopicID,
+	Relationships.RelationshipKey,
+	Relationships.Target_TopicID,
+	Relationships.IsDeleted,
+	Relationships.Version
+FROM	Relationships
+WHERE	RowNumber		= 1
+
+--------------------------------------------------------------------------------------------------------------------------------
+-- SELECT REFERENCES
+--------------------------------------------------------------------------------------------------------------------------------
+;WITH TopicReferences AS (
+  SELECT	Source_TopicID,
+	ReferenceKey,
+	Target_TopicID,
+	Version,
+	RowNumber = ROW_NUMBER() OVER (
+	  PARTITION BY		Source_TopicID,
+			ReferenceKey
+	  ORDER BY		Version	DESC
+	)
+  FROM	[dbo].[TopicReferences]
+  WHERE	Version		> @Since
+)
+SELECT	TopicReferences.Source_TopicID,
+	TopicReferences.ReferenceKey,
+	TopicReferences.Target_TopicID,
+	TopicReferences.Version
+FROM	TopicReferences
+WHERE	RowNumber		= 1
+
+--------------------------------------------------------------------------------------------------------------------------------
+-- SELECT HISTORY
+--------------------------------------------------------------------------------------------------------------------------------
+SELECT	TopicID,
+	Version
+FROM	VersionHistoryIndex
+WHERE	Version		> @Since