ERROR: Column >>?column?<< specified several times

Question

当我执行以下 UNION ALL 代码将多个表合并为一个实体化视图时，出现错误：column >>?column?<< specified several times。正如您在代码上方所见，我严格保留了原始表格中的顺序。

• 1. 名字
• 2. info1 AS hoehe
• 3. info1 作为艺术
• 4. info1 AS name_alternative
• 5. info2 AS 区域
• 6. info3 AS text_hoehe
• 7. kn AS name_lang
• 8. geoloc
• 9. 符号编号

---

DROP MATERIALIZED VIEW vt_views.poi_test;

CREATE MATERIALIZED VIEW vt_views.poi_test
TABLESPACE pg_default
AS
 SELECT tim_bergname.name,
 tim_bergname.info1 AS hoehe,
 NULL,
 NULL,
 tim_bergname.info2 AS region,
 NULL,
 NULL,
 tim_bergname.geoloc,
 tim_bergname.symbolnummer
 FROM tim_bergname

UNION ALL

SELECT tim_flurname.name,
 NULL,
 NULL,
 NULL,
 NULL,
 NULL,
 NULL,
 tim_flurname.geoloc,
 tim_flurname.symbolnummer
 FROM tim_flurname

UNION ALL

SELECT tim_haus_huette.name,
 NULL,
 tim_haus_huette.info1 AS art,
 NULL,
 tim_haus_huette.info2 AS region,
 NULL,
 NULL,
 tim_haus_huette.geoloc,
 tim_haus_huette.symbolnummer
 FROM tim_haus_huette

UNION ALL

SELECT tim_museum.name,
 NULL,
 tim_museum.info1 AS art,
 NULL,
 NULL,
 NULL,
 tim_museum.kn AS name_lang,
 tim_museum.geoloc,
 tim_museum.symbolnummer
 FROM tim_museum

UNION ALL

... several other SELECTS (shortened because of Whosebug restrictions)

UNION ALL

SELECT tim_wohnmobilstellplatz.name,
 NULL,
 NULL,
 NULL,
 NULL,
 NULL,
 NULL,
 tim_wohnmobilstellplatz.geoloc,
 tim_wohnmobilstellplatz.symbolnummer
 FROM tim_wohnmobilstellplatz


WITH DATA;

ALTER TABLE vt_views.poi_test
 OWNER TO postgres;

GRANT ALL ON TABLE vt_views.poi TO postgres;
GRANT ALL ON TABLE vt_views.poi TO PUBLIC;

知道这是为什么吗？是因为例如 info1 被使用了三次吗？我无法编辑原始表，因为我们有一批正在填充表。感谢您的帮助！

Answer 1

问题出在第一个查询中，针对 NULL 个条目。您应该命名相应的列：

SELECT tim_bergname.name,
 tim_bergname.info1 AS hoehe,
 NULL AS mycol1,
 NULL AS mycol2,
 tim_bergname.info2 AS region,
 NULL AS mycol3,
 NULL AS mycol4,
 tim_bergname.geoloc,
 tim_bergname.symbolnummer
 FROM tim_bergname