6.9.3 Effective scope of derived column names
The examples in the following tables illustrate the effective scope of derived column names.
|
Example SQL statement |
Effective scope |
||||
|---|---|---|---|---|---|
|
C1 |
C2 |
C3 |
DC3 |
C4 |
|
|
SELECT "C1","C2" |
Y |
Y |
N |
Y |
N |
|
|
Y |
Y |
N |
Y |
N |
|
|
N |
N |
Y |
N |
N |
|
|
N |
N |
Y |
N |
N |
|
|
N |
N |
Y |
N |
N |
|
|
N |
N |
N |
Y |
N |
|
|
Y |
Y |
N |
Y |
N |
|
|
Y |
Y |
N |
Y |
N |
|
|
N |
N |
N |
N |
Y |
|
|
Y |
Y |
N |
N |
Y |
|
|
Y |
Y |
N |
Y |
Y |
![[Figure]](GRAPHICS/F0000086.GIF)
FROM "T1",- Legend:
-
Y: Has scope.
N: Does not have scope.
T1,T2,T3: Table identifier
C1, C2: T1 column name
C3: T2 column name
C4: T3 column name
Y: Correlation name
DC3: Derived column name of derived table Y
|
Example SQL statement |
Effective scope |
||||||
|---|---|---|---|---|---|---|---|
|
C1 |
C2 |
GC2 |
C3 |
DC3 |
C4 |
C5 |
|
|
SELECT "C1","GC2" |
Y |
A |
Y |
N |
A |
N |
N |
|
|
Y |
Y |
N |
N |
Y |
N |
N |
|
|
N |
N |
N |
Y |
N |
N |
N |
|
|
N |
N |
N |
Y |
N |
N |
N |
|
|
N |
N |
N |
Y |
N |
N |
N |
|
|
N |
N |
N |
N |
Y |
N |
N |
|
|
Y |
Y |
N |
N |
Y |
N |
N |
|
|
Y |
Y |
N |
N |
Y |
N |
N |
|
|
N |
N |
N |
N |
N |
Y |
N |
|
|
Y |
Y |
N |
N |
Y |
Y |
N |
|
|
Y |
Y |
N |
N |
Y |
Y |
N |
|
|
Y |
Y |
N |
N |
Y |
N |
N |
|
|
Y |
A |
Y |
N |
A |
N |
N |
|
|
Y |
A |
Y |
N |
A |
N |
N |
|
|
N |
N |
N |
N |
N |
N |
Y |
|
|
Y |
N |
N |
N |
N |
N |
Y |
|
|
Y |
A |
N |
N |
A |
N |
Y |
- Legend:
-
Y: Has scope.
A: Has scope, but is not a grouping column, so can only be specified as the argument of a set function.
N: Does not have scope.
T1,T2,T3,T4: Table identifier
C1, C2: T1 column name
C3: T2 column name
C4: T3 column name
C5: T4 column name
GC2: the names of the grouping columns
Y: Correlation name
DC3: Derived column name of derived table Y