Question

当我为以下视图运行脚本时，出现此错误：

错误报告-
ORA-00936：缺少表达式
00936. 00000-“缺少表达式”
*原因：
*动作：

脚本：

CREATE OR REPLACE VIEW mainUser.studentData_view
(
    StudentID,
    StudentName,
    StudentDOB,
    StudentSubjectID,
    SubjectName,
    LastUpdated)

AS
    SELECT student.StudentID,
           student.StudentName,
           student.StudentDOB,
           student.StudentSubjectID,
           subject.SubjectName,
           audit.SYSTIMESTAMP
    FROM   mainuser.studentdata student,
           mainuser.studentdatachanges audit,
           mainuser.subjectdata subject
    WHERE  student.StudentSubjectID = subject.SubjectID
           AND AUD.systimestamp = (SELECT Max(SYSTIMESTAMP)
                                   FROM   mainuser.studentdatachanges AUD2
                                   WHERE  AUD2.NEW_StudentID = AUD.new_studentid);

Answer 1

您应该使用显式连接语法（JOIN关键字），这样可以使所有内容更加清晰。具有显式联接的查询如下所示：

SELECT ... --Removed to shorten query
FROM mainUser.studentData student
JOIN mainUser.studentDataChanges audit --Missing join predicate
JOIN mainUser.subjectData subject ON student.StudentSubjectID = subject.SubjectID
WHERE AUD.SYSTIMESTAMP = (SELECT MAX(SYSTIMESTAMP) 
                          FROM mainUser.studentDataChanges AUD2 
                          WHERE AUD2.NEW_StudentID = AUD.NEW_StudentID);

这里需要注意的几件事：

studentDataChanges的别名为audit，然后称为AUD。需要选择两个之一
studentDataChanges缺少连接谓词（也许AUD.StudentID = student.StudentID吗？）

它看起来像这样：

SELECT ...
FROM mainUser.studentData student
JOIN mainUser.studentDataChanges AUD ON AUD.StudentID = student.StudentID 
JOIN mainUser.subjectData subject ON student.StudentSubjectID = subject.SubjectID
WHERE AUD.SYSTIMESTAMP = (SELECT MAX(SYSTIMESTAMP) 
                          FROM mainUser.studentDataChanges AUD2 
                          WHERE AUD2.NEW_StudentID = AUD.NEW_StudentID);

00936. 00000-创建视图时出现“缺少表达式”

1 个答案: