从逗号分隔的ID获取逗号分隔的文本

Question

我有两个表，tblStudent和tblDepartment。我将DeptIds以逗号分隔值的形式存储在学生表中，例如-

StudentId  DeptIds
1          1,2,3
2          4
3          1,5

我想在学生表的GetById过程中用逗号而不是DeptIds分隔部门名称。有什么帮助吗？

Answer 1

首先，更改数据模型，使其不包含DeptIds CSV列值

从您的问题中可以看出，这是非常不切实际的，使用更好的数据模型是永远不会发生的。

我建议使用以下数据模型：

• tblStudent表具有最少的学生数据（id，姓名，姓氏，出生日期...）
• tbl部门表，部门数据最少（id，dept_name，dept_group ...）
• tblStudentDept作为中间表，具有连接数据（StudentId，DeptId，ActivityInd，date_from，date_until ...）

这样，您将使用tblStudentDept表逐行存储有关特定部门中学生角色的数据：

ID  StudentId  DeptIds    
 1   1          1
 2   1          2
 3   1          3   
 4   2          4
 5   3          1
 6   3          5

之后，您可以使用LISTAGG函数显示CSV数据

对于ID，就像以前一样：

在WITH AS中带有测试数据示例的代码：

WITH tblStudentDept AS(
    select 1 as id, 1 as StudentID, 1 as DeptID from dual
    union all
    select 2 as id, 1 as StudentID, 2 as DeptID from dual
    union all
    select 3 as id, 1 as StudentID, 3 as DeptID from dual
    union all
    select 4 as id, 2 as StudentID, 4 as DeptID from dual
    union all
    select 5 as id, 3 as StudentID, 1 as DeptID from dual
    union all
    select 6 as id, 3 as StudentID, 5 as DeptID from dual
)
SELECT sd.StudentID, LISTAGG(DeptID, ',') WITHIN GROUP (ORDER BY sd.DeptID)
  FROM tblStudentDept sd
 GROUP BY sd.StudentID;

按部门要求输入部门名称：

使用WITH AS表和希望新建的tblDepartment表之间的连接，在tblStudentDept中包含测试数据示例的代码：

WITH tblStudentDept AS(
    select 1 as id, 1 as StudentID, 1 as DeptID from dual
    union all
    select 2 as id, 1 as StudentID, 2 as DeptID from dual
    union all
    select 3 as id, 1 as StudentID, 3 as DeptID from dual
    union all
    select 4 as id, 2 as StudentID, 4 as DeptID from dual
    union all
    select 5 as id, 3 as StudentID, 1 as DeptID from dual
    union all
    select 6 as id, 3 as StudentID, 5 as DeptID from dual
),
tblDepartment AS(
    select 1 as DeptId, 'Dept-1' as DeptName from dual
    union all
    select 2 as DeptId, 'Dept-2' as DeptName from dual
    union all
    select 3 as DeptId, 'Dept-3' as DeptName from dual
    union all
    select 4 as DeptId, 'Dept-4' as DeptName from dual
    union all
    select 5 as DeptId, 'Dept-5' as DeptName from dual
)
SELECT sd.StudentID, LISTAGG(d.DeptName, ',') WITHIN GROUP (ORDER BY sd.DeptID) as DeptNames
  FROM tblStudentDept sd
  JOIN tblDepartment d
    ON (d.DeptId = sd.DeptId)
 GROUP BY sd.StudentID;

代码输出：

StudentId  DeptNames    
 1          Dept-1,Dept-2,Dept-3
 2          Dept-4
 3          Dept-1,Dept-5

希望我能帮上忙！