将值从一个表插入到另一个MySQL

Question

我想将数据从我的一个表插入到另一个表。这是我拥有的已填充表：

 Act (
 id  INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
 birth_date DATETIME,
 death_date DATETIME,
 place VARCHAR(20)  
 );

在此表中，某些值是NULL-例如，如果是生育行为，则death_date是NULL。

这是我要将数据传输到的表：

 Population_Growth (
 id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
 number_of_births INT,
 number_of_deaths INT,
 place VARCHAR(20),
 time DATE
 );

最后，我希望该表显示同一地点和同一日期的死亡人数和出生人数。 至于出生和死亡的数量，我会做这样的事情：

INSERT INTO Population_Growth (number_of_births, number_of_deaths) VALUES 
((COUNT (birth_date) FROM Act WHERE birth_date IS NOT NULL)), 
((COUNT (death_date) FROM Act WHERE death_date IS NOT NULL));

但是我不知道如何将其与相应的时间和日期联系起来。

Answer 1

获得指定结果的一种方法是像这样的查询：

SELECT c.place
     , c.time
     , SUM(c.count_births) AS number_of_births
     , SUM(c.count_deaths) AS number_of_deaths
  FROM (
         SELECT b.place
              , DATE(b.birth_date) AS `time`
              , SUM(1) AS count_births
              , SUM(0) AS count_deaths
           FROM Act b
          WHERE b.birth_date IS NOT NULL
          GROUP BY b.place, DATE(b.birth_date)
          UNION ALL
         SELECT d.place
              , DATE(d.death_date) AS `time`
              , SUM(0) AS count_births
              , SUM(1) AS count_deaths
           FROM Act d
          WHERE d.death_date IS NOT NULL
          GROUP BY d.place, DATE(d.death_date)
       ) c
  GROUP BY c.place, c.time

要将其转换为插入，请在SELECT之前添加：

INSERT INTO Population_Growth (place, `time`, number_of_births, number_of_deaths)

---

跟进

上面的查询将DATETIME列转换为DATE数据类型（通过截断时间部分）。

要按年和月获取摘要，但仍是可用于分配给DATE列的有效表格，一种选择是替换所有表达式：

DATE(b.birth_date)
DATE(d.death_date)

（在上面的查询中）具有以下表达式：

DATE_FORMAT(b.birth_date,'%Y-%m-01')
DATE_FORMAT(d.death_date,'%Y-%m-01')

新的表达式将从DATETIME列中提取年份和月份，并将日期部分设置为该月的1号。

Answer 2

如果我理解正确，则希望从两个日期列中获取非NULL值的计数。 这是获取摘要的一种方法：

select place, d,
       (select count(*) from act where act.birth_date = pd.d and act.place = pd.place) as births,
       (select count(*) from act where act.death_date = pd.d and act.place = pd.place) as deaths
from (select place, birth_date as d from act union
      select place, death_date from act
     ) pd;

然后，您可以通过执行以下操作将其放入population_growth ：

INSERT INTO Population_Growth(place, time, number_of_births, number_of_deaths) 
    select place, d,
           (select count(*) from act where act.birth_date = pd.d and act.place = pd.place) as births,
           (select count(*) from act where act.death_date = pd.d and act.place = pd.place) as deaths
    from (select place, birth_date as d from act union
          select place, death_date from act
         ) pd;