SQLite - Get all other rows with any duplicate column value
sqlite&gt; select
   ...&gt;    Username,
   ...&gt;    Field1,
   ...&gt;    Field2,
   ...&gt;    Field3,
   ...&gt;    (select u2.Username from User u2 where u2.Username&lt;&gt;u1.Username and u2.Field1=u1.field1)  as F1check,           ...&gt;    (select u2.Username from User u2 where u2.Username&lt;&gt;u1.Username and u2.Field2=u1.field2)  as F2check,           ...&gt;    (select u2.Username from User u2 where u2.Username&lt;&gt;u1.Username and u2.Field3=u1.field3)  as F2check
   ...&gt; from User u1;
Username    field1      field2      field3      F1check     F2check     F2check
----------  ----------  ----------  ----------  ----------  ----------  ----------
UserNum1    AAABBB      CCCDDD      EEEFFF      UserNum2    UserNum3
UserNum2    AAABBB      IIIJJJ      KKKFFF      UserNum1
UserNum3    LLLMMM      CCCDDD      PPPQQQ                  UserNum1
UserNum4    RRRSSS      TTTUUU      VVVWWW
sqlite&gt;


NOTE: if you have more values that are double, only the first one is show, i.e. if you have also this record:

insert into User values ('Usernum5','AAABBB','XXXYYY','XXXYYY')

then the output will show:

sqlite&gt; select
   ...&gt;    Username,
   ...&gt;    Field1,
   ...&gt;    Field2,
   ...&gt;    Field3,
   ...&gt;    (select u2.Username from User u2 where u2.Username&lt;&gt;u1.Username and u2.Field1=u1.field1)  as F1check,           ...&gt;    (select u2.Username from User u2 where u2.Username&lt;&gt;u1.Username and u2.Field2=u1.field2)  as F2check,           ...&gt;    (select u2.Username from User u2 where u2.Username&lt;&gt;u1.Username and u2.Field3=u1.field3)  as F2check
   ...&gt; from User u1;
Username    field1      field2      field3      F1check     F2check     F2check
----------  ----------  ----------  ----------  ----------  ----------  ----------
UserNum1    AAABBB      CCCDDD      EEEFFF      UserNum2    UserNum3
UserNum2    AAABBB      IIIJJJ      KKKFFF      UserNum1
UserNum3    LLLMMM      CCCDDD      PPPQQQ                  UserNum1
UserNum4    RRRSSS      TTTUUU      VVVWWW
Usernum5    AAABBB      XXXYYY      XXXYYY      UserNum1
sqlite&gt;


Where you see (on the line 'Usernum5') only a reference to Usernum1, and not to Usernum2.