SELECT borocode, SUM (totpop), SUM (sq_miles)
, SUM (totpop) / SUM (sq_miles) pop_density_pr_sqm
FROM public.uscb_acs_14to18_age
GROUP BY borocode
这个代码只显示自治区代码,我希望它也显示自治区名称
您可以使用类似max
的聚合函数作为"寄生的";
SELECT borocode, max(boroname), SUM (totpop), SUM (sq_miles)
, SUM (totpop) / SUM (sq_miles) pop_density_pr_sqm
FROM public.uscb_acs_14to18_age
GROUP BY borocode;
或者通过表达式列表将CCD_ 2添加到该组中。
SELECT borocode, boroname, SUM (totpop), SUM (sq_miles)
, SUM (totpop) / SUM (sq_miles) pop_density_pr_sqm
FROM public.uscb_acs_14to18_age
GROUP BY borocode, boroname;
如果borocode
是表的主键,那么甚至不需要按列表在组中列出非聚合表达式。