Question

我有以下MySQL语句，该语句从3个表中为我收集数据。

表具有以下结构：

旅行计划

#   Name        Type            
1   id          int(11)         
2   plan        varchar(11)         
3   created_at  timestamp               
4   updated_at  timestamp       
5   created_by  int(11)                 
6   updated_by  int(11)             
7   eligibility varchar(50)     
8   lower_limit int(11)             
9   upper_limit int(11)

plan_category

#   Name        Type    
1   idPrimary   int(11)         
2   category    varchar(255)            
3   created_at  timestamp                   
4   updated_at  timestamp       
5   updated_by  int(11)             
6   created_by  int(11)

plan_category_detail

#   Name                Type    
1   idPrimary           int(11) 
2   plan_category_id    int(11)         
3   travel_plan_id      int(11)     
4   description         varchar(255)        
5   created_at          timestamp           
6   updated_at          timestamp
7   created_by          int(11)     
8   updated_by          int(11)

这是我的SQL查询：

SELECT 
  plan_category.id,
  plan_category.category AS OPTION,
  CASE
    WHEN plan = 'Business' THEN plan_category_detail.description
    ELSE ''
  END AS Business,
  CASE
    WHEN plan = 'Holiday' THEN plan_category_detail.description
    ELSE ''
  END AS Holiday,
  CASE
    WHEN plan = 'Schengen' THEN plan_category_detail.description
    ELSE ''
  END AS Schengen,
  CASE
    WHEN plan = 'Student' THEN plan_category_detail.description
    ELSE ''
  END AS Student,
  CASE
    WHEN plan = 'Senior' THEN plan_category_detail.description
    ELSE ''
  END AS Senior,
  CASE
    WHEN plan = 'Incoming' THEN plan_category_detail.description
    ELSE ''
  END AS Incoming,
  CASE
    WHEN plan = 'East Africa' THEN plan_category_detail.description
    ELSE ''
  END AS East_Africa
FROM
  travel_plan
    INNER JOIN
  plan_category_detail ON plan_category_detail.travel_plan_id = travel_plan.id
    INNER JOIN
  plan_category ON plan_category.id = plan_category_detail.plan_category_id
GROUP BY plan_Category_detail.id , plan_category.id;

它给了我以下输出：

"1" "LIMIT (Medical Expenses and Related Expenses)" "300,000"   ""  ""  ""  ""  ""  ""
"1" "LIMIT (Medical Expenses and Related Expenses)" ""  "200,000"   ""  ""  ""  ""  ""
"1" "LIMIT (Medical Expenses and Related Expenses)" ""  ""  "80,000"    ""  ""  ""  ""
"1" "LIMIT (Medical Expenses and Related Expenses)" ""  ""  ""  "75,000"    ""  ""  ""
"1" "LIMIT (Medical Expenses and Related Expenses)" ""  ""  ""  ""  "100,000"   ""  ""
"1" "LIMIT (Medical Expenses and Related Expenses)" ""  ""  ""  ""  ""  "120,000"   ""
"1" "LIMIT (Medical Expenses and Related Expenses)" ""  ""  ""  ""  ""  ""  "30,000"

但是，我想要以下类型的输出：

"1" "LIMIT (Medical Expenses and Related Expenses)" "300,000"   "200,000"   "80,000"    "75,000"    "100,000"   "120,000"   "30,000"

如何实现以上输出？

我也尝试了GROUP BY函数，但仍然无法正常工作。请帮助

Answer 1

这里需要一个Category 1 > Category 1.1 >，因此只需在案例表达式中使用conditional aggregation

max()

MySQL Select与CASE AND Group By

1 个答案: