postgresql 将从具有不同模式的两个 SELECT 语句“生成”的结果连接到一个表中
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Join results "generated" from two SELECT statements with different schemas into one table
提问by Martin Marinov
So I have the following SELECT statements:
所以我有以下 SELECT 语句：
SELECT COUNT(A.Award) AS US, SUBSTRING(CAST(M.Year as char(4)), 0 , 4) AS Decade
FROM Movies M, Awards A
WHERE {SOME WHERE CLAUSE}
GROUP BY Decade;
and
和
SELECT COUNT(*) AS Total, SUBSTRING(CAST(A2.Year as char(4)), 0 , 4) AS Decade
FROM Awards A2
WHERE {SOME WHERE CLAUSE}
GROUP BY Decade;
The first one is "generating" a table with columns (US, Decade) and the second one is "generating" another table with columns (Total, Decade). I want to join those two tables so that I get a table (US, Total, Decade). How can I do it?
第一个是“生成”一个带有列（US，Decade）的表，第二个是“生成”另一个带有列（Total，Decade）的表。我想加入这两个表，以便我得到一个表（US，Total，Decade）。我该怎么做？
回答by knittl
Put them in subqueries and do a JOIN:
将它们放在子查询中并执行以下操作JOIN：
SELECT a.US, a.decade, b.total FROM
(SELECT COUNT(A.Award) AS US, SUBSTRING(CAST(M.Year as char(4)), 0 , 4) AS Decade
FROM Movies M, Awards A
WHERE {SOME WHERE CLAUSE}
GROUP BY Decade ) AS a
INNER JOIN
(SELECT COUNT(*) AS Total, SUBSTRING(CAST(A2.Year as char(4)), 0 , 4) AS Decade
FROM Awards A2
WHERE {SOME WHERE CLAUSE}
GROUP BY Decade) AS b
ON a.decade = b.decade
