合并所有产品
本课属于 Coddy SQL 学习旅程的“基础知识”单元。第 55 课,共 72 课。
挑战
中等可用的表和列:
enom_gilpane:part_id,rpm,watt,sizecastle_loctus:part_id,rpm,watt,sizehonpan_bilopsa:part_id,rpm,watt,sizeyurnol_qoltam:part_id,rpm,watt,size
现在计算所有产品相同的质量分数(每张表代表一个产品),并使用 UNION ALL 将它们合并:
quality_table as (
SELECT * FROM filtered_quality_1
UNION ALL
SELECT * FROM filtered_quality_2
UNION ALL
SELECT * FROM filtered_quality_3
UNION ALL
SELECT * FROM filtered_quality_4
)返回 part_id 和 quality
亲手试试
-- 第一个产品的数据块已为你完成,沿用上一课的内容
WITH filtered_enom_gilpane_quality as (
WITH enom_gilpane_quality as (
SELECT part_id, ((rpm * watt) / size) as quality
FROM (
SELECT part_id, rpm, watt + (select avg(watt) from enom_gilpane) as watt, size
FROM enom_gilpane
)
)
SELECT *
FROM enom_gilpane_quality
WHERE quality > (select avg(quality) from enom_gilpane_quality)
),
-- 为下面的三个产品表分别构建相同的数据块
filtered_castle_loctus_quality as (
____
),
filtered_honpan_bilopsa_quality as (
____
),
filtered_yurnol_qoltam_quality as (
____
),
-- 将四个数据块依次合并,保留所有行
quality_table as (
SELECT * FROM filtered_enom_gilpane_quality
____
)
SELECT ____
FROM quality_table基础知识中的所有课
自己练习: SQL 在线编辑器