Mysql 基于数据库表其他行中的值设置一列的值_Mysql

Mysql 基于数据库表其他行中的值设置一列的值

mysql

Mysql 基于数据库表其他行中的值设置一列的值,mysql,Mysql,我有一张这样的桌子： | Date | Name | Activity | +------------+------+----------+ | 2018-01-01 | A | 1 | | 2018-01-01 | B | 0 | | 2018-01-01 | C | 0 | | 2018-02-01 | A | 0 | | 2018-02-01 | B | 1 | | 2018-0

我有一张这样的桌子：

| Date       | Name | Activity |
+------------+------+----------+
| 2018-01-01 | A    | 1        |
| 2018-01-01 | B    | 0        |
| 2018-01-01 | C    | 0        |
| 2018-02-01 | A    | 0        |
| 2018-02-01 | B    | 1        |
| 2018-02-01 | C    | 0        |
| 2018-03-01 | A    | 0        |
| 2018-03-01 | B    | 0        |
| 2018-03-01 | C    | 0        |

我需要添加一列

status

，该列根据

activity

列中的值为名称显示为active或inactive

例如：

如果在1月份，名称A的活动为1，则状态应为“活动”
如果在2月份，名称A的活动为1，则应仅显示为活动；如果名称A为0，则应显示为活动，因为在1月份，名称A的活动为活动，因此在整个过程中，名称A应显示为活动
只有在上个月的数据中其活动为0，而本月的活动为1时，我们才应该更改数据

所以，我想要得到的结果是：

| Date       | Name | Activity | Status |
+------------+------+----------+--------+
| 2018-01-01 | A    | 1        | A      |
| 2018-01-01 | B    | 0        | I      |
| 2018-01-01 | C    | 0        | I      |
| 2018-02-01 | A    | 0        | A      |
| 2018-02-01 | B    | 1        | A      |
| 2018-02-01 | C    | 0        | I      |
| 2018-03-01 | A    | 0        | A      |
| 2018-03-01 | B    | 0        | A      |
| 2018-03-01 | C    | 0        | I      |

MySQL 5.6架构设置：

create table user_activity(id int(11) not null auto_increment,
                           month date,name varchar(15),
                           activity enum('A','I'),primary key(id) );

 insert into user_activity (month,name,activity) values('2019-01-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-02-01','alpha','I');

 insert into user_activity (month,name,activity) values('2019-03-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-01-01','beta','A');

  insert into user_activity (month,name,activity) values('2019-02-01','beta','I');

select * from user_activity

| id |      month |  name | activity |
|----|------------|-------|----------|
|  1 | 2019-01-01 | alpha |        A |
|  2 | 2019-02-01 | alpha |        I |
|  3 | 2019-03-01 | alpha |        A |
|  4 | 2019-01-01 |  beta |        A |
|  5 | 2019-02-01 |  beta |        I |

select max(month),name,activity
from user_activity
where activity='A'
group by name

| max(month) |  name | activity |
|------------|-------|----------|
| 2019-03-01 | alpha |        A |
| 2019-01-01 |  beta |        A |

查询1：

create table user_activity(id int(11) not null auto_increment,
                           month date,name varchar(15),
                           activity enum('A','I'),primary key(id) );

 insert into user_activity (month,name,activity) values('2019-01-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-02-01','alpha','I');

 insert into user_activity (month,name,activity) values('2019-03-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-01-01','beta','A');

  insert into user_activity (month,name,activity) values('2019-02-01','beta','I');

select * from user_activity

| id |      month |  name | activity |
|----|------------|-------|----------|
|  1 | 2019-01-01 | alpha |        A |
|  2 | 2019-02-01 | alpha |        I |
|  3 | 2019-03-01 | alpha |        A |
|  4 | 2019-01-01 |  beta |        A |
|  5 | 2019-02-01 |  beta |        I |

select max(month),name,activity
from user_activity
where activity='A'
group by name

| max(month) |  name | activity |
|------------|-------|----------|
| 2019-03-01 | alpha |        A |
| 2019-01-01 |  beta |        A |

[结果][2]：

create table user_activity(id int(11) not null auto_increment,
                           month date,name varchar(15),
                           activity enum('A','I'),primary key(id) );

 insert into user_activity (month,name,activity) values('2019-01-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-02-01','alpha','I');

 insert into user_activity (month,name,activity) values('2019-03-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-01-01','beta','A');

  insert into user_activity (month,name,activity) values('2019-02-01','beta','I');

select * from user_activity

| id |      month |  name | activity |
|----|------------|-------|----------|
|  1 | 2019-01-01 | alpha |        A |
|  2 | 2019-02-01 | alpha |        I |
|  3 | 2019-03-01 | alpha |        A |
|  4 | 2019-01-01 |  beta |        A |
|  5 | 2019-02-01 |  beta |        I |

select max(month),name,activity
from user_activity
where activity='A'
group by name

| max(month) |  name | activity |
|------------|-------|----------|
| 2019-03-01 | alpha |        A |
| 2019-01-01 |  beta |        A |

查询2：

create table user_activity(id int(11) not null auto_increment,
                           month date,name varchar(15),
                           activity enum('A','I'),primary key(id) );

 insert into user_activity (month,name,activity) values('2019-01-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-02-01','alpha','I');

 insert into user_activity (month,name,activity) values('2019-03-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-01-01','beta','A');

  insert into user_activity (month,name,activity) values('2019-02-01','beta','I');

select * from user_activity

| id |      month |  name | activity |
|----|------------|-------|----------|
|  1 | 2019-01-01 | alpha |        A |
|  2 | 2019-02-01 | alpha |        I |
|  3 | 2019-03-01 | alpha |        A |
|  4 | 2019-01-01 |  beta |        A |
|  5 | 2019-02-01 |  beta |        I |

select max(month),name,activity
from user_activity
where activity='A'
group by name

| max(month) |  name | activity |
|------------|-------|----------|
| 2019-03-01 | alpha |        A |
| 2019-01-01 |  beta |        A |

[结果][3]：

create table user_activity(id int(11) not null auto_increment,
                           month date,name varchar(15),
                           activity enum('A','I'),primary key(id) );

 insert into user_activity (month,name,activity) values('2019-01-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-02-01','alpha','I');

 insert into user_activity (month,name,activity) values('2019-03-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-01-01','beta','A');

  insert into user_activity (month,name,activity) values('2019-02-01','beta','I');

select * from user_activity

| id |      month |  name | activity |
|----|------------|-------|----------|
|  1 | 2019-01-01 | alpha |        A |
|  2 | 2019-02-01 | alpha |        I |
|  3 | 2019-03-01 | alpha |        A |
|  4 | 2019-01-01 |  beta |        A |
|  5 | 2019-02-01 |  beta |        I |

select max(month),name,activity
from user_activity
where activity='A'
group by name

| max(month) |  name | activity |
|------------|-------|----------|
| 2019-03-01 | alpha |        A |
| 2019-01-01 |  beta |        A |

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