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98
comment_list AS
(
SELECT n_comment
FROM nation_list
),
name_list AS
(
SELECT n_name
FROM nation_list
)
SELECT n_comment
FROM comment_list
UNION ALL
SELECT n_name
FROM name_list;
You might reasonably expect only the unique attributes to be
SELECT
ed from the
nation_baseline
table, but as the query profile shown in Figure 3-19, you also see the
highlighted attribute
N_REGIONKEY
, which is not referenced in any CTE or the main body.
ChapTer 3
The Query profiler