Dear gurus,

I have custom object1 named Case_Type_Data__c with Level_1__c, Level_2__c,Level_3__c
and i have another custom object2 named  ERT_Case_Type__c with same fields Level_1__c, Level_2__c,Level_3__c

A batch copied data from ERT_Case_Type__c to Case_Type_Data__c

Now i try to write SOQL in workbench to find out which records didnt get copied
 

Select Level_1__c,Level_2__c,Level_3__c From Case_Type_Data__c Where Level_3__c NOT IN (Select Level_3__c From ERT_Case_Type__c)

Workbench throws error

MALFORMED_QUERY: semi join sub selects can only query id fields, cannot use: 'Level_3__c'

Please note Id of ERT_Case_Type__c and Id of Case_Type_Data__c doesnt matches hence cant use Id

Please provide me a Join SOQL to get records which didn't got copied from ERT_Case_Type__c to Case_Type_Data__c
Regards
Fiona