Question

感谢大家: ()我有4个表格项目、要点、步骤和评论;

Project id name desc

points id name desc project_id

steps id desc points_id

comments id desc steps_id

我像这样写了查询

SELECT * FROM Project 
INNER JOIN points ON points.project_id=Project.id
INNER JOIN steps ON steps.points_id=points.id
INNER JOIN comments ON comments.steps_id=steps.id
WHERE Project.id=333

one project has many points, points, has many steps, and it has many comments somthing like this, and i whant to get all results in one query otherwise it takes a lot of time get results :(( i have no idea what can i do to :((

是这样子的

**Project**
id :1,
name :"get",

**points**
id :1,
name :"points1", ///project "get" s point
project_id : 1,
id :2,
name :"points2", ///project "get" s point
project_id : 1,

**steps**
id :1,
name :"steps1", ///project "points2" s step
points_id : 2,
id :2,
name :"steps2",///project "points2" s step
points_id : 2,

**comments**
id :1,
name :"something", ///project "steps1" s comment
steps_id : 1,
id :2,
name :"something",///project "steps2" s comment
steps_id : 2,

) ) )))(如果有其他办法解决这个问题?谢谢支持 :())))))

Answer 1

首先,您有一个无效的 sql 语法。您错过了关键字 < code> FROM 。它应该是 :

SELECT * 
FROM Table1
       INNER JOIN table2 ON table2.table1_id= table1.id
       INNER JOIN table3 ON table3.table2_id= table2.id
       INNER JOIN table4 ON table4.table3_id= table3.id
WHERE table1.ID = 333

但我需要你的预期结果。您需要指定您的数据库图案和假记录来完成查询。

Answer 2

在您张贴的查询中遗漏了几件东西 :

Missing FROM clause
Also, every join is not correct like table2.table1_id= table1.id ... it should be table2.table2_id= table1.id (Unless your table design is like so)

所以,最终你的查询应该看起来像

SELECT *  FROM Table1        
INNER JOIN table2 ON table2.table2_id= table1.id        
INNER JOIN table3 ON table3.table2_id= table1.id        
INNER JOIN table4 ON table4.table4_id= table1.id 
WHERE table1.ID = 333

Answer 3

您正在通过以 333 来过滤 ID 来从表1 中获取所有列。从其它表格中再获取一列如何? 您期待什么?

Answer 4

最后一个INNER JOIN中有一个打字机。表2应该是表4。

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