Question

我有一个表有重复的日期和时间，有些日期有重复的时间，但是真的想用SQL查询把它算作1，distinct不工作，也不知道怎么做这个任何帮助？目的是计算每天每个寄存器号的下载量。例如，2018-01-08具有重复的开始时间，应计为1.

我的查询不是这样做的。

Select  StartDate, Starttime, count(*) AS TOTALDOWNLOAD, RegisterNumber 
FROM            `SAMPLE.csv`
WHERE        (MaintenanceFlightTime > 0)
group by StartDate,Starttime, RegisterNumber

RegisterNumber  StartDate   StartTime
    A         2017-11-27    19:22:17
    A         2017-11-27    19:45:39
    B         2017-11-29    14:09:30
    A         2017-11-28    21:51:38
    A         2017-11-30    17:09:34
    B         2017-12-01    15:19:35
    A         2017-12-01    19:31:42
    B         2017-12-02    14:59:28
    B         2017-12-03    17:38:39
    B         2017-12-03    19:09:19
    B         2017-12-04    10:16:24
    B         2017-12-04    13:43:37
    B         2017-12-05    06:37:22
    A         2017-12-05    10:24:37
    A         2017-12-05    14:40:19
    B         2017-12-05    19:44:06
    A         2017-12-06    08:26:55
    A         2017-12-06    06:30:38
    A         2017-12-06    11:35:41
    A         2018-01-08    06:40:52
    A         2018-01-08    06:40:52
    A         2018-01-08    06:40:52
    A         2018-01-08    06:40:52
    A         2018-01-08    06:40:52
    A         2018-01-08    06:40:52
    A         2018-01-08    06:40:52
    A         2018-01-08    06:40:52

Answer 1

试试这个：

at 
org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:137) ~[spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:122) ~[spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
    at com.zophop.gps.ZophopFrontEndServer.main(ZophopFrontEndServer.java:16) [classes!/:0.0.3]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_171]

Answer 2

您应该只在结果集中包含group by所需的行。因此，如果您想计算每RegisterNumber天的数量，您可以使用：

SELECT RegisterNumber, COUNT(DISTINCT StartDate)
FROM `SAMPLE.csv`
WHERE MaintenanceFlightTime > 0
GROUP BY RegisterNumber ;

如果要计算日期和时间的不同组合，则某些数据库允许您将COUNT(DISTINCT)与多个参数一起使用：

SELECT RegisterNumber, COUNT(DISTINCT StartDate, StartTime)
FROM `SAMPLE.csv`
WHERE MaintenanceFlightTime > 0
GROUP BY RegisterNumber ;

在其他情况下，您需要使用字符串连接或日期/时间函数将值组合到单个列中。在极端情况下，您还可以使用子查询：

SELECT RegisterNumber, COUNT(*)
FROM (SELECT DISTINCT RegisterNumber, StartDate, StartTime
      FROM `SAMPLE.csv`
      WHERE MaintenanceFlightTime > 0
     ) s
GROUP BY RegisterNumber ;

使用带有重复日期和时间的Count

2 个答案: