where not exist

[SB2021]

The below code will have an extra row on ID E  with value 8 .

 By using where not exist this row should not be loaded.  I want to know why it will load. I have a hypothesis but not sure about that.

T1:
LOAD * Inline [

ID, brand, value
A , abc , 5
B, XYZ , 6
C , XYZ , 7
C , abc, 8
];

T2:
load ID1 as ID ,brand , value ;

LOAD * Inline [

ID1 , brand , value
A , abc , 500
B, pqr , 6
E , XYZ, 70000
E , abc , 8// will be loaded why?
]   where not Exists(ID,ID1 ) ;

[jwjackso · Accepted solution]

ID1 has not been renamed to ID, so the value 'E' does not exist in filed ID and both records are loaded. If you move the test to 

T2:

Load ID1 as ID, brand, value

where not Exists (ID,ID1);

you will get the results that you expect.