我有一张叫做“升降机”的桌子：
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| ID | USERNAME | lift_ID | DATE |
-----------------------------------------------------
| 1 | user1 | 0 | 2013-06-01 |
-----------------------------------------------------
| 2 | user1 | 0 | 2013-06-03 |
-----------------------------------------------------
| 3 | user1 | 1 | 2013-06-03 |
-----------------------------------------------------
| 4 | user2 | 0 | 2013-06-04 |
-----------------------------------------------------
| 5 | user2 | 1 | 2013-06-04 |
-----------------------------------------------------
| 6 | user2 | 1 | 2013-06-05 |
-----------------------------------------------------
| 7 | user1 | 2 | 2013-06-03 |
我想从特定用户中选择所有不同的lift_id，其中日期是该用户lift_id的最新日期。
如果我愿意为user1做，我会得到：
-----------------------------------------------------
| 2 | user1 | 0 | 2013-06-03 |
-----------------------------------------------------
| 3 | user1 | 1 | 2013-06-03 |
-----------------------------------------------------
| 7 | user1 | 2 | 2013-06-03 |
我试过了：
SELECT *
FROM lift l1
WHERE date` = (
SELECT MAX(date)
FROM lift
WHERE l1.lift_id = lift.lift_id)
AND username = 'user1'
ORDER BY lift_id ASC
)
;
在最大日期选择了所有不同的提升，但没有考虑到我想要的不同用户。
答案 0 :(得分：4)
您的查询已结束。在子查询中需要一个额外的关联子句：
SELECT l.*
FROM lift l
WHERE l.date = (select max(l2.date)
from lift l2
where l2.lift_id = l.lift_id and
l2.username = l.username
) and
l.username = 'user1'
ORDER BY l.lift_id ASC;
答案 1 :(得分：0)
您可以使用TMIN：
> dput(kk)
structure(list(INDICATIVO = structure(c(1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = c("8008A",
"8036B", "8251E", "8325C", "8433I", "8472B", "8496E", "8520B"
), class = "factor"), ANYO = c(2015L, 2015L, 2015L, 2015L, 2015L,
2015L, 2015L, 2015L, 2015L, 2015L, 2016L, 2016L, 2016L, 2016L,
2016L, 2016L, 2016L, 2016L, 2016L, 2016L), MES = c(3L, 4L, 5L,
6L, 7L, 8L, 9L, 10L, 11L, 12L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L,
9L, 10L), NOMBRE = structure(c(8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L,
8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L), .Label = c("ALGEMESSI AUMAR",
"ARENOS (C.H. JUCAR)", "BENIDORM (AQUAGEST)", "CAUDIEL-MAS DE NOGUERA",
"EMBALSE DE ALCORA", "LA POBLA DE BENIFASS\xc0-FREDES I.", "VILLARGORDO DEL CABRIEL-CONTRERAS",
"VILLENA"), class = "factor"), ALTITUD = c(486L, 486L, 486L,
486L, 486L, 486L, 486L, 486L, 486L, 486L, 486L, 486L, 486L, 486L,
486L, 486L, 486L, 486L, 486L, 486L), NOM_PROV = structure(c(1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L), .Label = c("ALICANTE", "CASTELLON", "VALENCIA"), class = "factor"),
LONGITUD = c(51562L, 51562L, 51562L, 51562L, 51562L, 51562L,
51562L, 51562L, 51562L, 51562L, 51562L, 51562L, 51562L, 51562L,
51562L, 51562L, 51562L, 51562L, 51562L, 51562L), LATITUD = c(383437L,
383437L, 383437L, 383437L, 383437L, 383437L, 383437L, 383437L,
383437L, 383437L, 383437L, 383437L, 383437L, 383437L, 383437L,
383437L, 383437L, 383437L, 383437L, 383437L), DATUM = structure(c(1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L), .Label = "ETRS89", class = "factor"), TMAX1 = c(230L,
220L, 310L, 280L, 370L, 310L, 330L, 270L, 200L, 180L, 180L,
190L, 170L, 160L, 210L, 290L, 340L, 320L, 300L, 310L), TMAX2 = c(270L,
200L, 310L, 295L, 330L, 330L, 310L, 270L, 160L, 195L, 150L,
200L, 220L, 180L, 225L, 290L, 360L, 330L, 330L, 300L), TMAX3 = c(240L,
220L, 370L, 300L, 370L, 250L, 330L, 230L, 190L, 200L, 170L,
170L, 180L, 190L, 240L, 290L, 340L, 360L, 350L, 290L), TMAX4 = c(230L,
200L, 330L, 300L, 380L, 360L, 290L, 290L, 230L, 200L, 210L,
130L, 220L, 190L, 230L, 300L, 320L, 400L, 390L, 300L), TMAX5 = c(180L,
240L, 290L, 310L, 400L, 360L, 240L, 300L, 220L, 180L, 170L,
140L, 140L, 120L, 170L, 290L, 360L, 330L, 425L, 270L), TMAX6 = c(170L,
150L, 290L, 320L, 390L, 360L, 190L, 280L, 235L, 160L, 110L,
180L, 140L, 180L, 210L, 310L, 340L, 310L, 360L, 330L), TMAX7 = c(250L,
150L, 260L, 310L, 425L, 400L, 220L, 250L, 230L, 160L, 190L,
130L, 90L, 195L, 190L, 310L, 310L, 310L, 340L, 310L), TMAX8 = c(180L,
170L, 290L, 320L, 400L, 325L, 250L, 220L, 200L, 200L, 220L,
160L, 140L, 150L, 180L, 340L, 360L, 340L, 340L, 290L), TMAX9 = c(200L,
180L, 290L, 330L, 340L, 330L, 240L, 230L, 220L, 160L, 200L,
180L, 140L, 200L, 190L, 360L, 350L, 330L, 320L, 270L), TMAX10 = c(195L,
200L, 270L, 310L, 360L, 390L, 320L, 250L, 240L, 135L, 170L,
210L, 120L, 190L, 190L, 350L, 360L, 250L, 320L, 260L), TMAX11 = c(260L,
180L, 310L, 240L, 340L, 350L, 300L, 270L, 230L, 140L, 100L,
210L, 150L, 200L, 210L, 320L, 370L, 290L, 300L, 300L), TMAX12 = c(260L,
190L, 340L, 300L, 355L, 380L, 290L, 270L, 190L, 140L, 140L,
220L, 130L, 230L, 210L, 310L, 370L, 290L, 320L, 230L), TMAX13 = c(185L,
200L, 380L, 290L, 360L, 350L, 320L, 240L, 210L, 170L, 150L,
220L, 150L, 200L, 210L, 375L, 300L, 300L, 300L, 190L), TMAX14 = c(160L,
260L, 415L, 170L, 360L, 320L, 300L, 230L, 200L, 180L, 160L,
170L, 150L, 230L, 240L, 350L, 280L, 310L, 250L, 230L), TMAX15 = c(130L,
230L, 390L, 260L, 360L, 300L, 300L, 250L, 200L, 210L, 120L,
140L, 150L, 240L, 230L, 320L, 270L, 320L, 260L, 240L), TMAX16 = c(150L,
240L, 370L, 270L, 360L, 300L, 330L, 230L, 230L, 215L, 160L,
120L, 180L, 250L, 230L, 270L, 280L, 260L, 290L, 250L), TMAX17 = c(140L,
260L, 380L, 300L, 370L, 350L, 270L, 230L, 230L, 210L, 130L,
130L, 150L, 240L, 220L, 280L, 310L, 375L, 300L, 290L), TMAX18 = c(120L,
250L, 280L, 280L, 350L, 320L, 250L, 240L, 220L, 215L, 170L,
130L, 160L, 220L, 250L, 300L, 320L, 370L, 280L, 230L), TMAX19 = c(140L,
240L, 280L, 320L, 380L, 320L, 265L, 220L, 240L, 220L, 140L,
120L, 150L, 180L, 260L, 280L, 340L, 370L, 300L, 220L), TMAX20 = c(120L,
215L, 230L, 310L, 370L, 330L, 290L, 190L, 260L, 180L, 150L,
160L, 170L, 200L, 250L, 280L, 380L, 390L, 270L, 220L), TMAX21 = c(170L,
200L, 220L, 310L, 370L, 330L, 330L, 200L, 200L, 185L, 140L,
170L, 140L, 230L, 250L, 295L, 360L, 300L, 310L, 200L), TMAX22 = c(140L,
240L, 220L, 400L, 370L, 330L, 340L, 210L, 130L, 155L, 160L,
220L, 130L, 210L, 300L, 310L, 340L, 320L, 310L, 210L), TMAX23 = c(160L,
270L, 240L, 350L, 340L, 340L, 300L, 230L, 100L, 160L, 190L,
180L, 170L, 230L, 240L, 320L, 310L, 330L, 290L, 240L), TMAX24 = c(150L,
250L, 230L, 310L, 390L, 330L, 260L, 190L, 130L, 150L, 190L,
200L, 200L, 240L, 270L, 350L, 310L, 330L, 280L, NA), TMAX25 = c(110L,
260L, 250L, 310L, 350L, 320L, 280L, 190L, 180L, 160L, 190L,
160L, 230L, 200L, 300L, 330L, 310L, 330L, 290L, NA), TMAX26 = c(150L,
260L, 290L, 335L, 340L, 320L, 280L, 190L, 190L, 160L, 140L,
160L, 240L, 250L, 280L, 300L, 325L, 310L, 280L, NA), TMAX27 = c(230L,
220L, 260L, 360L, 420L, 330L, 260L, 230L, 160L, 160L, 130L,
85L, 210L, 250L, 300L, 320L, 340L, 340L, 270L, NA), TMAX28 = c(260L,
250L, 260L, 390L, 350L, 350L, 230L, 200L, 190L, 160L, 170L,
150L, 170L, 220L, 300L, 320L, 330L, 360L, 240L, NA), TMAX29 = c(260L,
250L, 300L, 370L, 390L, 330L, 210L, 230L, 180L, 180L, 130L,
150L, 250L, 130L, 260L, 330L, 350L, 350L, 260L, NA), TMAX30 = c(280L,
260L, 300L, 370L, 340L, 315L, 230L, 220L, 230L, 180L, 170L,
NA, 240L, 240L, 290L, 350L, 380L, 310L, 270L, NA), TMAX31 = c(310L,
NA, 290L, NA, 330L, 340L, NA, 200L, NA, 210L, 210L, NA, 175L,
NA, 270L, NA, 400L, 310L, NA, NA), TMIN1 = c(70L, 60L, 70L,
130L, 160L, 210L, 210L, 130L, 90L, -50L, 50L, 20L, 20L, 40L,
90L, 90L, 170L, 240L, 155L, 110L), TMIN2 = c(130L, 20L, 140L,
130L, 200L, 210L, 190L, 90L, 60L, -15L, 30L, -10L, 40L, -10L,
10L, 100L, 140L, 150L, 150L, 130L), TMIN3 = c(70L, 30L, 90L,
100L, 210L, 190L, 165L, 100L, 60L, -10L, 35L, 10L, 80L, 30L,
30L, 130L, 210L, 140L, 130L, 110L), TMIN4 = c(70L, 80L, 150L,
90L, 190L, 180L, 200L, 120L, 50L, 0L, 120L, -10L, -10L, 70L,
30L, 130L, 200L, 160L, 130L, 110L), TMIN5 = c(-20L, 100L,
150L, 100L, 150L, 220L, 170L, 150L, 90L, -10L, 70L, 20L,
60L, 80L, 55L, 120L, 180L, 210L, 160L, 150L), TMIN6 = c(-30L,
55L, 135L, 80L, 150L, 230L, 170L, 130L, 90L, 70L, 50L, 10L,
35L, 100L, 70L, 110L, 190L, 170L, 190L, 120L), TMIN7 = c(-30L,
80L, 70L, 70L, 150L, 240L, 170L, 120L, 100L, 80L, 40L, 65L,
-20L, 75L, 90L, 130L, 160L, 130L, 140L, 130L), TMIN8 = c(30L,
50L, 70L, 100L, 180L, 200L, 150L, 120L, 90L, 40L, 10L, 95L,
20L, 50L, 90L, 125L, 170L, 150L, 150L, 120L), TMIN9 = c(50L,
80L, 110L, 110L, 210L, 210L, 125L, 100L, 80L, 30L, 85L, 60L,
-20L, 0L, 110L, 140L, 210L, 130L, 160L, 140L), TMIN10 = c(-10L,
70L, 70L, 80L, 180L, 230L, 180L, 100L, 30L, 30L, 50L, 130L,
40L, 20L, 80L, 160L, 160L, 180L, 150L, 120L), TMIN11 = c(-10L,
80L, 50L, 110L, 160L, 220L, 170L, 130L, 25L, 30L, 50L, 120L,
-20L, 50L, 100L, 180L, 170L, 140L, 210L, 150L), TMIN12 = c(20L,
90L, 60L, 150L, 180L, 210L, 140L, 120L, 25L, 30L, 20L, 90L,
-10L, 50L, 75L, 160L, 180L, 140L, 140L, 100L), TMIN13 = c(20L,
110L, 80L, 150L, 160L, 200L, 150L, 140L, 100L, 20L, -15L,
160L, -30L, 60L, 100L, 150L, 200L, 105L, 140L, 120L), TMIN14 = c(20L,
70L, 120L, 130L, 160L, 190L, 180L, 130L, 100L, 0L, -15L,
70L, -10L, 40L, 110L, 220L, 200L, 120L, 140L, 90L), TMIN15 = c(-5L,
115L, 110L, 140L, 170L, 180L, 125L, 40L, 60L, 0L, 40L, 60L,
40L, 50L, 110L, 170L, 180L, 120L, 80L, 60L), TMIN16 = c(50L,
100L, 60L, 100L, 155L, 160L, 120L, 115L, 50L, 20L, -30L,
55L, 10L, 50L, 80L, 170L, 150L, 160L, 100L, 50L), TMIN17 = c(-10L,
80L, 60L, 110L, 170L, 210L, 140L, 90L, 40L, 5L, -60L, -80L,
5L, 100L, 50L, 120L, 100L, 155L, 90L, 110L), TMIN18 = c(70L,
50L, 50L, 120L, 170L, 205L, 120L, 100L, 0L, 0L, 70L, 0L,
90L, 80L, 60L, 100L, 130L, 185L, 110L, 160L), TMIN19 = c(100L,
90L, 160L, 120L, 180L, 220L, 140L, 100L, 30L, -10L, 50L,
70L, 100L, 110L, 80L, 100L, 130L, 180L, 100L, 160L), TMIN20 = c(110L,
60L, 130L, 120L, 190L, 200L, 100L, 140L, 50L, -30L, -15L,
-15L, 50L, 110L, 80L, 110L, 180L, 200L, 160L, 130L), TMIN21 = c(90L,
40L, 80L, 130L, 175L, 175L, 120L, 90L, 50L, -10L, 0L, 40L,
50L, 80L, 80L, 100L, 170L, 220L, 140L, 130L), TMIN22 = c(100L,
100L, 60L, 130L, 195L, 175L, 120L, 70L, -10L, 0L, 25L, 60L,
80L, 80L, 80L, 100L, 150L, 170L, 130L, 110L), TMIN23 = c(70L,
70L, 50L, 150L, 190L, 170L, 130L, 50L, -10L, 20L, 15L, 20L,
85L, 50L, 120L, 110L, 180L, 150L, 130L, 150L), TMIN24 = c(80L,
60L, 60L, 140L, 200L, 210L, 100L, 90L, -45L, 0L, 20L, 20L,
25L, 80L, 100L, 110L, 140L, 135L, 125L, 130L), TMIN25 = c(30L,
110L, 65L, 150L, 230L, 150L, 90L, 130L, -20L, -20L, 70L,
90L, 20L, 40L, 110L, 125L, 140L, 130L, 135L, NA), TMIN26 = c(10L,
110L, 80L, 150L, 230L, 150L, 90L, 130L, 100L, 20L, 40L, 20L,
115L, 40L, 130L, 170L, 140L, 145L, 185L, NA), TMIN27 = c(70L,
100L, 100L, 150L, 200L, 140L, 130L, 120L, 10L, 35L, 40L,
40L, 70L, 70L, 120L, 170L, 150L, 140L, 160L, NA), TMIN28 = c(70L,
90L, 90L, 150L, 200L, 140L, 110L, 70L, 10L, -20L, 25L, 40L,
90L, 120L, 150L, 170L, 160L, 160L, 170L, NA), TMIN29 = c(60L,
60L, 90L, 150L, 200L, 160L, 100L, 80L, -30L, 50L, 60L, 60L,
75L, 110L, 150L, 200L, 140L, 200L, 120L, NA), TMIN30 = c(90L,
60L, 70L, 150L, 210L, 170L, 130L, 65L, -10L, 0L, 60L, NA,
10L, 110L, 140L, 180L, 170L, 220L, 130L, NA), TMIN31 = c(110L,
NA, 130L, NA, 210L, 220L, NA, 100L, NA, 70L, 80L, NA, 65L,
NA, 120L, NA, 210L, 170L, NA, NA)), .Names = c("INDICATIVO",
"ANYO", "MES", "NOMBRE", "ALTITUD", "NOM_PROV", "LONGITUD", "LATITUD",
"DATUM", "TMAX1", "TMAX2", "TMAX3", "TMAX4", "TMAX5", "TMAX6",
"TMAX7", "TMAX8", "TMAX9", "TMAX10", "TMAX11", "TMAX12", "TMAX13",
"TMAX14", "TMAX15", "TMAX16", "TMAX17", "TMAX18", "TMAX19", "TMAX20",
"TMAX21", "TMAX22", "TMAX23", "TMAX24", "TMAX25", "TMAX26", "TMAX27",
"TMAX28", "TMAX29", "TMAX30", "TMAX31", "TMIN1", "TMIN2", "TMIN3",
"TMIN4", "TMIN5", "TMIN6", "TMIN7", "TMIN8", "TMIN9", "TMIN10",
"TMIN11", "TMIN12", "TMIN13", "TMIN14", "TMIN15", "TMIN16", "TMIN17",
"TMIN18", "TMIN19", "TMIN20", "TMIN21", "TMIN22", "TMIN23", "TMIN24",
"TMIN25", "TMIN26", "TMIN27", "TMIN28", "TMIN29", "TMIN30", "TMIN31"
), row.names = 786:805, class = "data.frame")