如何使用动态mysql制作先验表

Question

我有 3 个这样的表

create table order_match
(
id int(10) PRIMARY KEY not null,
order_status_id int(10) not null
);

create table order_match_detail
(
 id int(10) PRIMARY KEY not null,
 order_match_id int(10) not null,
 product_id int(10) NOT NULL
);

create table product
(
id int(10) PRIMARY KEY not null,
name varchar(255) not null
);

Insert into order_match (id, order_status_id)
select 1, 6 union all
select 2, 7 union all
select 3, 6 union all
select 4, 6;

Insert into order_match_detail (id, order_match_id, product_id)
select 1, 1, 147  union all
select 2, 2, 148 union all
select 3, 3, 147 union all
select 4, 4, 149 union all
select 5, 4, 147;

Insert into product (id, name)
select 147, 'orange' union all
select 148, 'carrot' union all
select 149, 'Apple';

order_match.id = order_match_detail.order_match_id 和order_match_detail.product_id = product.id

我想将order_status_id 不在 7 中的数据设为成功交易，从该成功交易开始，如果交易购买苹果，则苹果的列包含 1 否则如果不购买，则 0这是我的预期结果，我想将这些数据用于分析

 id (in order_match)    |    Orange  |  Carrot  |   Apple
    
    1                           1            0           0
    3                           1            0           0
    4                           1            0           1 

这个问题我可以用这个查询来解决

select om.id,
  count(DISTINCT case when omd.product_id = 147 THEN 1 END) Orange,
  count(DISTINCT case when omd.product_id = 148 THEN 1 END) Carrot,
  count(DISTINCT case when omd.product_id = 149 THEN 1 END) Apple
  from order_match om
left join order_match_detail omd
  on om.id = omd.order_match_id
where om.order_status_id in (4, 5, 6, 8)
group by om.id

真正的问题是，在我的真实数据库中，它包含 1550 product_id，如何使其自动生成，因此无需手动输入 product_id 直到 1550 product_id

这是小提琴https://dbfiddle.uk/?rdbms=mysql_5.7&fiddle=c0eb7fe1b012ab1c909d37e325a8d434

我已经尝试过这样的新查询，但仍然错误

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'count(case when product.name = ''',
      product.name,
      ''' then 1 end) AS ',
      replace(product.name, ' ', '')
    )
  ) INTO @sql
from product;

SET @sql = CONCAT('SELECT omd.order_match_id, ', @sql, ' from order_match_detail omd
left join order_match om
  on omd.order_match_id = om.id
left join product p
  on omd.product_id = p.id
where om.order_status_id in (4, 5, 6, 8)
group by omd.order_match_id');

PREPARE stmt FROM @sql;
EXECUTE stmt;

Answer 1

您的查询几乎是正确的，您在别名而不是 p 上缺少您应该在第二个查询中使用“产品”，它会起作用

         SET group_concat_max_len = 1000000;
SET @sql = NULL;
    SELECT
      GROUP_CONCAT(DISTINCT
        CONCAT(
           'count(case when product.name = ''',
          product.name,
          ''' then 1 end) AS ',
          '"',replace(product.name, ' ', ''),'"'
        )
      )  INTO @sql
    from product;
    
    SET @sql = CONCAT('SELECT omd.order_match_id as id, ', @sql, ' from order_match_detail omd
    left join order_match om
      on omd.order_match_id = om.id
    left join product product
      on omd.product_id = product.id
    where om.order_status_id in (4, 5, 6, 8)
    group by omd.order_match_id');
    PREPARE stmt FROM @sql;
    EXECUTE stmt;
             

如果您确定产品 ID 对每个 ID 都有唯一的名称，您可以从 GROUP_CONCAT(DISTINCT 中删除 DISTINCT

然后我会得到你在问题中提到的exact 结果，否则你会看到，Apple 列在前，Orange 列在后，总体结果为expected。