SQL数据透视和分组查询

有人能帮我解决以下问题吗？ 情况如下，我有下表：

信号名 价值 日期 报警 10 2020-01-01 警告 7. 2020-01-01 检查 4. 2020-01-01 报警 1. 2020-01-02 警告 4. 2020-01-02 检查 3. 2020-01-02

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示例的pivot语法应该如下所示：

SELECT *
from(select * from table) src 
PIVOT (sum(value) FOR signalName in ([Alarm],[Warning],[Check]))  pvt

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您也可以使用max（）代替sum（）

示例中的pivot语法如下所示：

SELECT *
from(select * from table) src 
PIVOT (sum(value) FOR signalName in ([Alarm],[Warning],[Check]))  pvt

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你也可以用max（）代替sum（）

这里我分享两种解决问题的方法：

模式：

 create table mytable (signalName varchar(20),  value   int, date date)
 insert into mytable values('Alarm',    10, '2020-01-01');
 insert into mytable values('Warning',  7,  '2020-01-01');
 insert into mytable values('Check',    4,  '2020-01-01');
 insert into mytable values('Alarm',    1,  '2020-01-02');
 insert into mytable values('Warning',  4,  '2020-01-02');
 insert into mytable values('Check',    3,  '2020-01-02');

 select max(case when signalname='Alarm' then value end)ValueAlarm,
  max(case when signalname='Warning' then value end )ValueWarning,
   max(case when signalname='Check' then value end )ValueCheck,
   date
   from mytable
   group by date
   

具有简单聚合和分组依据的查询：

 create table mytable (signalName varchar(20),  value   int, date date)
 insert into mytable values('Alarm',    10, '2020-01-01');
 insert into mytable values('Warning',  7,  '2020-01-01');
 insert into mytable values('Check',    4,  '2020-01-01');
 insert into mytable values('Alarm',    1,  '2020-01-02');
 insert into mytable values('Warning',  4,  '2020-01-02');
 insert into mytable values('Check',    3,  '2020-01-02');

 select max(case when signalname='Alarm' then value end)ValueAlarm,
  max(case when signalname='Warning' then value end )ValueWarning,
   max(case when signalname='Check' then value end )ValueCheck,
   date
   from mytable
   group by date
   

输出：

 create table mytable (signalName varchar(20),  value   int, date date)
 insert into mytable values('Alarm',    10, '2020-01-01');
 insert into mytable values('Warning',  7,  '2020-01-01');
 insert into mytable values('Check',    4,  '2020-01-01');
 insert into mytable values('Alarm',    1,  '2020-01-02');
 insert into mytable values('Warning',  4,  '2020-01-02');
 insert into mytable values('Check',    3,  '2020-01-02');

 select max(case when signalname='Alarm' then value end)ValueAlarm,
  max(case when signalname='Warning' then value end )ValueWarning,
   max(case when signalname='Check' then value end )ValueCheck,
   date
   from mytable
   group by date
   

价值警报 价值警告 价值检查 日期 10 7. 4. 2020-01-01 1. 4. 3. 2020-01-02

---

在这里，我分享两种解决您问题的方法：

模式：

 create table mytable (signalName varchar(20),  value   int, date date)
 insert into mytable values('Alarm',    10, '2020-01-01');
 insert into mytable values('Warning',  7,  '2020-01-01');
 insert into mytable values('Check',    4,  '2020-01-01');
 insert into mytable values('Alarm',    1,  '2020-01-02');
 insert into mytable values('Warning',  4,  '2020-01-02');
 insert into mytable values('Check',    3,  '2020-01-02');

 select max(case when signalname='Alarm' then value end)ValueAlarm,
  max(case when signalname='Warning' then value end )ValueWarning,
   max(case when signalname='Check' then value end )ValueCheck,
   date
   from mytable
   group by date
   

具有简单聚合和分组依据的查询：

 create table mytable (signalName varchar(20),  value   int, date date)
 insert into mytable values('Alarm',    10, '2020-01-01');
 insert into mytable values('Warning',  7,  '2020-01-01');
 insert into mytable values('Check',    4,  '2020-01-01');
 insert into mytable values('Alarm',    1,  '2020-01-02');
 insert into mytable values('Warning',  4,  '2020-01-02');
 insert into mytable values('Check',    3,  '2020-01-02');

 select max(case when signalname='Alarm' then value end)ValueAlarm,
  max(case when signalname='Warning' then value end )ValueWarning,
   max(case when signalname='Check' then value end )ValueCheck,
   date
   from mytable
   group by date
   

输出：

 create table mytable (signalName varchar(20),  value   int, date date)
 insert into mytable values('Alarm',    10, '2020-01-01');
 insert into mytable values('Warning',  7,  '2020-01-01');
 insert into mytable values('Check',    4,  '2020-01-01');
 insert into mytable values('Alarm',    1,  '2020-01-02');
 insert into mytable values('Warning',  4,  '2020-01-02');
 insert into mytable values('Check',    3,  '2020-01-02');

 select max(case when signalname='Alarm' then value end)ValueAlarm,
  max(case when signalname='Warning' then value end )ValueWarning,
   max(case when signalname='Check' then value end )ValueCheck,
   date
   from mytable
   group by date
   

价值警报 价值警告 价值检查 日期 10 7. 4. 2020-01-01 1. 4. 3. 2020-01-02

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到目前为止你的尝试是什么？为什么你所做的一切都不起作用呢？那么你目前的努力如何呢？为什么你的东西不管用？