Select语句上的Postgresql连接
我想在Postgresql中对Select语句进行联接,但遇到了一些问题Select语句上的Postgresql连接,sql,postgresql,join,Sql,Postgresql,Join,我想在Postgresql中对Select语句进行联接,但遇到了一些问题 SELECT s.sessionid, sp.lang FROM sessions s INNER JOIN pages sp ON sp.sessionid = s.sessionid INNER JOIN ( SELECT max(sessionid) FROM sessions AS maxS
SELECT
s.sessionid, sp.lang
FROM
sessions s
INNER JOIN
pages sp
ON
sp.sessionid = s.sessionid
INNER JOIN
(
SELECT
max(sessionid)
FROM
sessions
AS
maxSession
)
ON
maxSession = s.sessionid
WHERE
--Where condition
我得到以下错误:
错误:“发件人”中的子查询必须具有别名
LINE 6: (
^
HINT: For example, FROM (SELECT ...) [AS] foo.
如果我从中添加
我又犯了一个错误
ERROR: syntax error at or near "FROM"
LINE 7: FROM
想法?你很接近了
INNER JOIN
(
SELECT
max(sessionid) as 'maxSession'
FROM
sessions
) maxSession
ON
maxSession.maxSession = s.sessionid
任何时候将查询引用为表时,都需要给它一个别名…别名位于整个子查询之后,而不是子查询本身。删除子查询上的别名。应该在外面。选择maxsessionid maxSession FROM sessions AS maxSession ON maxSession.maxSession=s.SessionDone更多信息缺失,您需要为maxsessionid提供别名是的,我这方面很马虎。修正了…刚刚注意到在我的答案发布之前,你在评论中出现了错误。
INNER JOIN
(
SELECT
max(sessionid) as 'maxSession'
FROM
sessions
) maxSession
ON
maxSession.maxSession = s.sessionid