Implement Create & Drop sequences

Author: hazzik

src/NHibernate/Dialect/Ingres9Dialect.cs

@@ -96,9 +96,19 @@ public override string GetSelectSequenceNextValString(string sequenceName)
 		{
 			return "next value for " + sequenceName;
 		}
-    
+
+		public override string GetCreateSequenceString(string sequenceName)
+		{
+			return "create sequence " + sequenceName;
+		}
+
+		public override string GetDropSequenceString(string sequenceName)
+		{
+			return "drop sequence " + sequenceName;
+		}
+
 		#region Overridden informational metadata
-		
+
 		public override bool DoesRepeatableReadCauseReadersToBlockWriters => true;
 
 		#endregion