The first form list is "Standard", with a field of "Code"; The second document list is "Attachments", which has a lookup field that can be multiple values of the Standard Codes. For expample:
Form List :
- StandardTitle Code -QAProcess Q1 -QARecordForm Q3 -OperationDaily O7
Document List :
- AttachmentTitle Code -QAReportSample Q1,Q3 -OperationSampleFile O7 -QAhours Q1
In a view of Form List one, there should be the list of files but only those with correct codes.
Form View 1:
-StandardTitle:QAProcess
-Code: Q1
-DocumentList:
1.QAReportSample 2.QAhours
Here I am looking for: Select AttachmentTitle from DocumentList where Code contains Q1
The last line is the problem. By default, the lookup field cannot be filtered! Anyone please kindly provides some suggestions? Thanks.
You can set a View for the List and Library. Also you can set view filters for Lookup. Select All Items view or create a new view, and apply filter for Code contains Q1, selected properties to title. Refer the below link.
SharePoint 2013 List Views