如何在MySql中使用递归查询?
WITH RECURSIVE transitive_closure(a, b, distance, path_string) AS( SELECT a, b, 1 AS distance,
a || '.' || b || '.' AS path_string,
b AS direct_connection
FROM edges2
WHERE a = 1 -- set the starting node
UNION ALL
SELECT tc.a, e.b, tc.distance + 1,
tc.path_string || e.b || '.' AS path_string,
tc.direct_connection
FROM edges2 AS e
JOIN transitive_closure AS tc ON e.a = tc.b
WHERE tc.path_string NOT LIKE '%' || e.b || '.%'
AND tc.distance < 3
)
SELECT * FROM transitive_closure
--WHERE b=3 -- set the target node
ORDER BY a,b,distance
如何在MySql中运行此查询?
它会显示如下错误消息:
#1064-您的SQL语法有误;检查与您的MySQL服务器版本相对应的手册以获取正确的语法,以在“ RECURSIVEtransiveive_closure(a,b,distance,path_string)AS(SELECT a,b,1 A''第1行附近使用)
回答:
该WITH RECURSIVE
语句/方法适用于PostgreSQL和Sybase(我想可能还有更多),所以也许您可以看一下:
http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html
它应该向您展示一些使用MySQL的方法(以及PHP中的一两个方法,我只知道它不在您的标签列表中)
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