Saving snapshots

Shogi.Database/Session/Tables/State.sql

@@ -0,0 +1,9 @@
+CREATE TABLE [session].[State]
+(
+	[Id] BIGINT NOT NULL PRIMARY KEY IDENTITY, 
+  [SessionId] [session].[SessionSurrogateKey] NOT NULL, 
+  [Document] NVARCHAR(MAX) NOT NULL,
+    
+  CONSTRAINT [FK_State_ToSession] FOREIGN KEY (SessionId) REFERENCES [session].[Session](Id),
+  CONSTRAINT [StateDocument must be JSON] CHECK(ISJSON(Document)=1)
+)