PL SQL：如何在同一个单元格中获得多个值？利斯特格，好的。但

Question

我是stackoverflow的新手，所以如果我问的不正确，请原谅。

我刚收到一张要求修改报告的票。

实际情况是，当一名员工参加培训时，有多个讲师，员工记录的重复次数与讲师人数一样多。

例如如下

---

Stud_id | ins_fname | ins_lname

---

001 |乌戈 |红色

---

001 |马可 |绿色

应该是

---

Stud_id | ins_fname | ins_lname

---

001 |乌戈，马可| 高分辨率照片| CLIPARTO红、绿

我知道有 LISTAGG 可以解决这个问题，但是它没有按应有的方式工作。

我猜是因为 stud_id 值是从嵌套表中提取的，所以我正在处理的报告看起来像这样

选择 col_1， col_2, ins_fname, ins_lname, col_n+1...n, 从 （选择不同的 stud.stud_id, col_n+1...n, 从表 ) 表名， 表名2， 表名3，

其中 1=1

这是否会影响 LISTAGG 的功能？

我得到的错误如下

列“I.MI”（在我试图列出的列之后）在选择列表中无效，因为 GROUP BY 子句或聚合函数不包含它：第 26 列第 7 行（在 pos 1010) 在 de.simplicit.vjdbc.util.SQLExceptionHelper.wrapSQLException（SQLExceptionHelper.java:44） 在 de.simplicit.vjdbc.util.SQLExceptionHelper.wrap(SQLExceptionHelper.java:25) 在 de.simplicit.vjdbc.server.command.CommandProcessor.process(CommandProcessor.java:165) 在 de.simplicit.vjdbc.server.servlet.ServletCommandSink.handleRequest(ServletCommandSink.java:176) 在 de.simplicit.vjdbc.server.servlet.ServletCommandSink.doPost(ServletCommandSink.java:150) 在 javax.servlet.http.HttpServlet.service(HttpServlet.java:648) 在 javax.servlet.http.HttpServlet.service(HttpServlet.java:729) 在 org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.

我知道这不是最清楚的问题，但我仍然非常感谢任何支持。

我使用的编译器是 Plateau Report Designer，它建立在 BIRT 之上，链接到 ORACLE db

谢谢大家，新年快乐

Answer 1

我想我理解了你的问题，它与分组有关！

我花时间重新创建了您的请求，这就是我可以使用 Oracle 的 LiveSQL 完成的操作

https://livesql.oracle.com/apex/livesql/s/hr0w91uigngd7wg5895ov7vc7

如果你没有Oracle的访问权限，你可以创建一个免费帐户，但以下是我编写的代码。

DROP TABLE training_instructor;
DROP TABLE training_enroll;
DROP TABLE employee;
DROP TABLE instructor;
DROP TABLE training;

CREATE TABLE employee(
  employee_id    NUMBER PRIMARY KEY
 ,employee_name  VARCHAR2(100)
);

CREATE TABLE instructor(
  instructor_id    NUMBER PRIMARY KEY
 ,instructor_name  VARCHAR2(100)
);

CREATE TABLE training(
  training_id    NUMBER   PRIMARY KEY
 ,training_name   VARCHAR2(100)
);

CREATE TABLE training_instructor(
  training_id    NUMBER
 ,instructor_id  NUMBER
 ,PRIMARY KEY(training_id, instructor_id)
);

CREATE TABLE training_enroll(
  training_id    NUMBER
 ,employee_id    NUMBER
 ,PRIMARY KEY(training_id, employee_id)
);

INSERT INTO employee VALUES(1,  'Employee 1');
INSERT INTO employee VALUES(2,  'Employee 2');
INSERT INTO employee VALUES(3,  'Employee 3');
INSERT INTO employee VALUES(4,  'Employee 4');
INSERT INTO employee VALUES(5,  'Employee 5');
INSERT INTO employee VALUES(6,  'Employee 6');
INSERT INTO employee VALUES(7,  'Employee 7');
INSERT INTO employee VALUES(8,  'Employee 8');
INSERT INTO employee VALUES(9,  'Employee 9');
INSERT INTO employee VALUES(10, 'Employee 10');
COMMIT;

INSERT INTO instructor VALUES(1, 'Instructor 1');
INSERT INTO instructor VALUES(2, 'Instructor 2');
INSERT INTO instructor VALUES(3, 'Instructor 3');
INSERT INTO instructor VALUES(4, 'Instructor 4');
INSERT INTO instructor VALUES(5, 'Instructor 5');
COMMIT;


INSERT INTO training VALUES(1, 'Training 1');
INSERT INTO training VALUES(2, 'Training 2');
INSERT INTO training VALUES(3, 'Training 3');
INSERT INTO training VALUES(4, 'Training 4');
INSERT INTO training VALUES(5, 'Training 5');
COMMIT;


INSERT INTO training_instructor VALUES(1, 1);
INSERT INTO training_instructor VALUES(2, 2);
INSERT INTO training_instructor VALUES(2, 3);
INSERT INTO training_instructor VALUES(3, 1);
INSERT INTO training_instructor VALUES(3, 3);
INSERT INTO training_instructor VALUES(3, 5);
INSERT INTO training_instructor VALUES(4, 2);
INSERT INTO training_instructor VALUES(4, 4);
INSERT INTO training_instructor VALUES(5, 4);
INSERT INTO training_instructor VALUES(5, 5);
COMMIT;


INSERT INTO training_enroll VALUES(1, 1);
INSERT INTO training_enroll VALUES(1, 2);
INSERT INTO training_enroll VALUES(1, 3);
INSERT INTO training_enroll VALUES(2, 6);
INSERT INTO training_enroll VALUES(2, 8);
INSERT INTO training_enroll VALUES(2, 10);
INSERT INTO training_enroll VALUES(2, 5);
INSERT INTO training_enroll VALUES(2, 4);
INSERT INTO training_enroll VALUES(3, 3);
INSERT INTO training_enroll VALUES(3, 5);
INSERT INTO training_enroll VALUES(3, 1);
INSERT INTO training_enroll VALUES(5, 10);
INSERT INTO training_enroll VALUES(5, 6);
COMMIT;
/
-- The final query
SELECT e.employee_id 
      ,e.employee_name 
      ,t.training_name 
      ,LISTAGG(i.instructor_name, ' | ')  WITHIN GROUP (ORDER BY i.instructor_name) instructor_list 
  FROM employee e 
       JOIN training_enroll te 
         ON e.employee_id = te.employee_id 
       JOIN training t 
         ON te.training_id = t.training_id 
       JOIN training_instructor ti 
         ON te.training_id = ti.training_id 
       JOIN instructor i 
         ON ti.instructor_id = i.instructor_id 
GROUP BY e.employee_id, e.employee_name, t.training_name 
ORDER BY e.employee_id, t.training_name