ORA-00918: 列在内部连接中定义不明确

Question

尝试使用内部连接创建视图时不断收到错误：

    CREATE OR REPLACE VIEW lab3view3
AS
SELECT 
       f.firstname,
       f.lastname,
       s.firstname,
       s.lastname,
       c.coursename, 
       sec.days, 
       TO_CHAR (sec.starttime, 'MM/DD/YYYY') AS startdate,
       TO_CHAR(sec.starttime, 'HH:MI AM    ') AS starttime,
       TO_CHAR(sec.endtime, 'MM/DD/YYYY') AS enddate, 
       TO_CHAR(sec.endtime, 'HH:MI AM    ') AS endtime,
       sec.sectionid,
       l.building, 
       l.room,
       g.grade
FROM  section sec
        INNER JOIN grade g
                    ON g.sectionid = sec.sectionid
        INNER JOIN course c
                    ON c.courseid = sec.courseid
        INNER JOIN location l
                    ON l.locationid = sec.locationid
        INNER JOIN student s
                    ON s.studentid = g.studentid
        INNER JOIN instructor i
                    ON i.sectionid = sec.sectionid
        INNER JOIN faculty f
                    ON f.facultyid = i.facultyid
        INNER JOIN section sec
                    ON sec.sectionid = g.sectionid; 

不断收到此错误：

第 1 行出错；

ORA-00918：列定义不明确

关于如何解决这个问题的任何想法？

Answer 1

您还需要在TO_CHAR（starttime 和endtime）调用中使用正确的表格作为时间前缀。您还从不同的表中选择了两次firstname 和lastname，第二个将被重命名为firstname_1 然后，它们必须重命名，因为您正在创建一个视图，请参阅@sstan's回答。

Answer 2

@maraca 的回答是正确的。但是一旦你修复了定义不明确的列错误，你就会得到

ORA-00957：列名重复

创建视图时，每个选定的列都需要有一个唯一的名称。确保在 select 子句中为重复的列名设置别名。

例子：

CREATE OR REPLACE VIEW lab3view3
    AS
    SELECT faculty.firstname as faculty_firstname,
           faculty.lastname as faculty_lastname,
           student.firstname as student_firstname,
           student.lastname as student_lastname,
...