diff --git a/server/AyaNova/biz/PartInventoryBiz.cs b/server/AyaNova/biz/PartInventoryBiz.cs
index 0d2167c0..8a29af54 100644
--- a/server/AyaNova/biz/PartInventoryBiz.cs
+++ b/server/AyaNova/biz/PartInventoryBiz.cs
@@ -43,22 +43,22 @@ namespace AyaNova.Biz
         //
         internal async Task<PartInventory> CreateAsync(PartInventory newObject)
         {
-            await ValidateAsync(newObject, null);
+            await ValidateAsync(newObject);
             if (HasErrors)
                 return null;
             else
             {
-               
+
                 await ct.PartInventory.AddAsync(newObject);
                 await ct.SaveChangesAsync();
                 await EventLogProcessor.LogEventToDatabaseAsync(new Event(UserId, newObject.Id, BizType, AyaEvent.Created), ct);
                 await SearchIndexAsync(newObject, true);
-               
+
                 return newObject;
             }
         }
 
-        
+
 
         ////////////////////////////////////////////////////////////////////////////////////////////////
         //GET 
@@ -71,7 +71,7 @@ namespace AyaNova.Biz
             return ret;
         }
 
-       
+
 
 
         ////////////////////////////////////////////////////////////////////////////////////////////////
@@ -107,31 +107,76 @@ namespace AyaNova.Biz
         //VALIDATION
         //
 
-        private async Task ValidateAsync(PartInventory proposedObj, PartInventory currentObj)
+        private async Task ValidateAsync(PartInventory proposedObj)
         {
 
-            bool isNew = currentObj == null;
-
-            //Name required
-            if (string.IsNullOrWhiteSpace(proposedObj.Name))
-                AddError(ApiErrorCode.VALIDATION_REQUIRED, "Name");
-
-
-
-            //If name is otherwise OK, check that name is unique
-            if (!PropertyHasErrors("Name"))
+            if (!await BizObjectExistsInDatabase.ExistsAsync(AyaType.Part, proposedObj.PartId, ct))
             {
-                //Use Any command is efficient way to check existance, it doesn't return the record, just a true or false
-                if (await ct.PartInventory.AnyAsync(m => m.Name == proposedObj.Name && m.Id != proposedObj.Id))
-                {
-                    AddError(ApiErrorCode.VALIDATION_NOT_UNIQUE, "Name");
-                }
+                AddError(ApiErrorCode.NOT_FOUND, "generalerror", $"PartInventory Part specified doesn't exist [id:{proposedObj.PartId}]");
+                return;
+            }
+
+            if (!await BizObjectExistsInDatabase.ExistsAsync(AyaType.PartWarehouse, proposedObj.PartWarehouseId, ct))
+            {
+                AddError(ApiErrorCode.NOT_FOUND, "generalerror", $"PartInventory PartWarehouse specified doesn't exist [id:{proposedObj.PartWarehouseId}]");
+                return;
+            }
+
+            if (proposedObj.SourceType != AyaType.NoType && proposedObj.SourceId != 0 && !await BizObjectExistsInDatabase.ExistsAsync(proposedObj.SourceType, proposedObj.SourceId, ct))
+            {
+                AddError(ApiErrorCode.NOT_FOUND, "generalerror", $"PartInventory source object causing inventory change specified doesn't exist [type:{proposedObj.SourceType}, id:{proposedObj.SourceId}]");
+                return;
             }
 
 
+            /*
+            "CONSTRAINT UNQ_PartInventory UNIQUE (sourceid, sourcetype, entrydate, balance), " +
+                "CONSTRAINT UNQ_PartInventory_Previous_values UNIQUE (sourceid, sourcetype, lastentrydate, lastbalance), " +
+                "CONSTRAINT fk_PartInventory_self FOREIGN KEY (sourceid, sourcetype, lastentrydate, lastbalance) references apartinventory(sourceid, sourcetype, entrydate, balance), " +
+                "CONSTRAINT CHK_PartInventory_Valid_Balance CHECK(balance >= 0 AND (balance = COALESCE(lastbalance, 0) + quantity)), " +
+                "CONSTRAINT CHK_PartInventory_Valid_Dates_Sequence CHECK(lastentrydate < entrydate), " +
+                "CONSTRAINT CHK_PartInventory_Valid_Previous_Columns CHECK((lastentrydate IS NULL AND lastbalance IS NULL) OR (lastentrydate IS NOT NULL AND lastbalance IS NOT NULL)) " +
+                            */
+
+            //New entry must have *something* to bank
+            if (proposedObj.Quantity == 0)
+            {
+                AddError(ApiErrorCode.VALIDATION_REQUIRED, "Quantity");
+                return;
+            }
+
+            //values must add up
+            if (proposedObj.LastBalance != null && proposedObj.Balance != proposedObj.LastBalance + proposedObj.Quantity)
+            {
+                AddError(ApiErrorCode.VALIDATION_INVALID_VALUE, "Balance", "Balance incorrect (LastBalance + Quantity not equal to Balance");
+                return;
+            }
+
+
+            //date is newer than last entry date?
+            if (proposedObj.LastEntryDate != null && proposedObj.LastEntryDate > proposedObj.EntryDate)
+            {
+                AddError(ApiErrorCode.VALIDATION_STARTDATE_AFTER_ENDDATE, "generalerror", "LastEntryDate is newer than EntryDate");
+                return;
+            }
+
+            //valid previous columns?
+            //either they're all null or none of them are null
+
+            //fix and re-test
+            if (!((proposedObj.LastEntryDate == null
+                && proposedObj.LastBalance == null) ||
+             (proposedObj.LastEntryDate != null
+              && proposedObj.LastBalance != null)
+             ))
+            {
+                AddError(ApiErrorCode.VALIDATION_INVALID_VALUE, "generalerror", "Last* entries must be all empty (opening entry) or none of them empty (any later entry)");
+                return;
+            }
+
         }
 
-      
+
 
         ////////////////////////////////////////////////////////////////////////////////////////////////
         //REPORTING