Databases Reference
In-Depth Information
CONCATENATE ([Aircrafts])
LOAD DISTINCT
[%Aircraft Type ID],
'Unknown: ' & [%Aircraft Type ID] as [Aircraft Name],
'Unknown' as [Aircraft
Group],
'UNKNOWN' as
[Manufacturer],
'???' as
[Aircraft Short Name]
RESIDENT Flights
WHERE NOT Exists(Temp_Aircraft_Type_ID, [%Aircraft Type ID]);
DROP TABLE Temp_Aircraft_Type_ID; // Clean up temporary table
3.
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Here's what the added script does:
1.
It copies all of the
%Aircraft Type ID
values from the
Aircrafts
dimension table into a separate, temporary field called
Temp_Aircraft_
Type_ID
.
° This separate field is necessary as we want to compare the
Aircraft
Type ID
values from the
Flights
table against only the
Aircraft
Type ID
values that exist in the
Aircrafts
table.
2.
We append a dummy table segment to the
Aircrafts
table by using the
WHERE NOT Exists(Temp_Aircraft_Type_ID, [%Aircraft Type ID])
clause. This helps us load the missing aircrafts from the
Flights
table while
also ruling out all aircrafts that are already stored in the original
Aircrafts
table, thus avoiding duplicates.
3.
At the same time, for each of the missing ID's, a dummy record is created
with (a variant of) the
Unknown
value for each corresponding attribute.
