After a lot of searching, I found: <https://github.com/UndefinedOffset/SortableGridField/blob/master/docs/ManyManyExample.md> for an example of usage.

However, implementing this code results in:

[User Error] Couldn't run query: SELECT DISTINCT MAX("SortOrder") FROM "Sidebar" INNER JOIN "TwoColumn\_Sidebars" ON "TwoColumn\_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn\_Sidebars"."TwoColumnID" = '2') Column 'SortOrder' in field list is ambiguous

I'm using SS3 and have SortableGridField installed (though no messages indicated successful installation upon running dev/build/?flush=all).

With Dev mode off, the CMS does not load ("Server Error"), however with Dev mode enabled, I get the above SQL error. Regardless, it seems to be working properly, I just need to find out why this error is being thrown.

UPDATE

Below is the top part of the stack traces generated on this error (there are 2 [User Error] blue headers on the page):

```
[User Error] Couldn't run query: SELECT DISTINCT MAX("SortOrder") FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') Column 'SortOrder' in field list is ambiguous
Couldn't run query: SELECT DISTINCT MAX("SortOrder") FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') Column 'SortOrder' in field list is ambiguous 
MySQLDatabase.php:580
MySQLDatabase->databaseError(Couldn't run query: SELECT DISTINCT MAX("SortOrder") FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') | Column 'SortOrder' in field list is ambiguous,256) 
MySQLDatabase.php:132
MySQLDatabase->query(SELECT DISTINCT MAX("SortOrder") FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2'),256) 
DB.php:200
DB::query(SELECT DISTINCT MAX("SortOrder") FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2'),256) 
SQLQuery.php:949
SQLQuery->execute() 
DataQuery.php:372
DataQuery->aggregate(MAX("SortOrder")) 
DataQuery.php:338
DataQuery->max(SortOrder) 
DataList.php:676
DataList->max(SortOrder) 
GridFieldSortableRows.php:148
GridFieldSortableRows->fixSortColumn(GridField,ManyManyList) 
GridFieldSortableRows.php:99
GridFieldSortableRows->getManipulatedData(GridField,ManyManyList) 
GridField.php:215
GridField->getManipulatedList() 
GridField.php:255
GridField->FieldHolder() 
...

[User Error] Couldn't run query: SELECT DISTINCT count(DISTINCT "Sidebar"."ID") AS "0" FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') AND ("SortOrder"=0) Column 'SortOrder' in where clause is ambiguous

Couldn't run query: SELECT DISTINCT count(DISTINCT "Sidebar"."ID") AS "0" FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') AND ("SortOrder"=0) Column 'SortOrder' in where clause is ambiguous 
MySQLDatabase.php:580
MySQLDatabase->databaseError(Couldn't run query: SELECT DISTINCT count(DISTINCT "Sidebar"."ID") AS "0" FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') AND ("SortOrder"=0) | Column 'SortOrder' in where clause is ambiguous,256) 
MySQLDatabase.php:132
MySQLDatabase->query(SELECT DISTINCT count(DISTINCT "Sidebar"."ID") AS "0" FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') AND ("SortOrder"=0),256) 
DB.php:200
DB::query(SELECT DISTINCT count(DISTINCT "Sidebar"."ID") AS "0" FROM "Sidebar" INNER JOIN "TwoColumn_Sidebars" ON "TwoColumn_Sidebars"."SidebarID" = "Sidebar"."ID" WHERE ("TwoColumn_Sidebars"."TwoColumnID" = '2') AND ("SortOrder"=0),256) 
SQLQuery.php:949
SQLQuery->execute() 
SQLQuery.php:1054
SQLQuery->count(DISTINCT "Sidebar"."ID") 
DataQuery.php:329
DataQuery->count() 
DataList.php:666
DataList->count() 
GridFieldSortableRows.php:150
GridFieldSortableRows->fixSortColumn(GridField,ManyManyList) 
GridFieldSortableRows.php:99
GridFieldSortableRows->getManipulatedData(GridField,ManyManyList) 
GridField.php:215
GridField->getManipulatedList() 
GridField.php:255
GridField->FieldHolder() 
ViewableData.php:366
ViewableData->obj(FieldHolder,,,1) 
...

```