Sql 获取两个日期之间每行的最大值?
在这里学习sql,我遇到了一个挑战 我有下表:Sql 获取两个日期之间每行的最大值?,sql,r,sqlite,sqldf,Sql,R,Sqlite,Sqldf,在这里学习sql,我遇到了一个挑战 我有下表: tbl <- data.frame( id_name = c("a", "a", "b", "c", "d", "f", "b", "c", "d", "f"), value = c(1, -1, 1, 1, 1, 1, -1, -1, -1, -1), score = c(1, 0, 1, 2, 3, 4, 3, 2, 1, 0), date = as.Date(c("2001-1-1", "2002-1-1", "
tbl <- data.frame(
id_name = c("a", "a", "b", "c", "d", "f", "b", "c", "d", "f"),
value = c(1, -1, 1, 1, 1, 1, -1, -1, -1, -1),
score = c(1, 0, 1, 2, 3, 4, 3, 2, 1, 0),
date = as.Date(c("2001-1-1", "2002-1-1", "2003-1-1", "2005-1-1",
"2005-1-1", "2007-1-1", "2008-1-1", "2010-1-1",
"2011-1-1", "2012-1-1"), "%Y-%m-%d")
)
+---------+-------+-------+-----------+
| id_name | value | score | date |
+---------+-------+-------+-----------+
| a | 1 | 1 | 2001-1-1 |
| a | -1 | 0 | 2002-1-1 |
| b | 1 | 1 | 2003-1-1 |
| c | 1 | 2 | 2005-1-1 |
| d | 1 | 3 | 2005-1-1 |
| f | 1 | 4 | 2007-1-1 |
| b | -1 | 3 | 2008-1-1 |
| c | -1 | 2 | 2010-1-1 |
| d | -1 | 1 | 2011-1-1 |
| f | -1 | 0 | 2012-1-1 |
+---------+-------+-------+-----------+
这就是我到目前为止所做的
sqldf("
SELECT
id_name,
date,
score
FROM
tbl As d
WHERE
score = (
SELECT MAX(score)
FROM tbl As b
WHERE
date >= (
SELECT MIN(date)
FROM tbl
WHERE id_name = b.id_name
) AND
date <= (
SELECT MAX(date)
FROM tbl
WHERE id_name = b.id_name
)
)
")
问题是,它返回的行具有全局最大值,而与当前行值无关
谢谢 我认为WHERE子句中的相关子查询适合这里的情况:
SELECT id_name, date
FROM tbl as t1
WHERE score = (SELECT max(score) FROM tbl WHERE id_name = t1.id_name)
谢谢你的回复。它让我更靠近了,但不太接近。例如,对于id_name='b',它应该返回'2007-1-1',因为这是得分最高的时候,并且介于id_name='b'的第一个和最后一个日期'2003-01-01'和'2008-01-01'之间,我更新了上面的问题和我的尝试。如果还不清楚,请告诉我。谢谢。那么您正在查找给定id_名称在两个日期之间出现的任何记录的最大分数的日期?您的id_名称是否只有1条记录或多于2条记录?另外,请澄清这是一个sqlite数据库?我在标签中看到了这一点,但我只是想确认一下,因为人们经常标记错误的RDBMS,如果他们的问题和正在使用的RDBMS在这里会起到很大的作用,因为LAG和其他窗口函数应该使这一点非常可行。是的,你的第一个问题,我在R中使用sqldf包做这件事,所以它是sqlite!
SELECT id_name, date
FROM tbl as t1
WHERE score = (SELECT max(score) FROM tbl WHERE id_name = t1.id_name)