两张桌子:COURSE_ROSTER - 包含
Two tables: COURSE_ROSTER - contains
- COURSE_ID 作为 COURSES 的外键
- USER_ID 作为我需要插入到 COURSES 的字段
- COURSE_ID as foreign key to COURSES
- USER_ID as field I need to insert into COURSES
COURSES - 包含
- COURSE_ID 作为主键
- INSTRUCTOR_ID 作为需要使用 COURSE_ROSTER 中的 USER_ID 字段更新的字段
- COURSE_ID as primary key
- INSTRUCTOR_ID as field that needs to be updated with USER_ID field from COURSE_ROSTER
UPDATE sql 语法是什么?我正在尝试这个,但不好...我遗漏了一些东西,我在网上找不到它.
What would the UPDATE sql syntax be? I am trying this, but no good... I'm missing something and I can't find it online.
UPDATE COURSES SET COURSES.INSTRUCTOR_ID = COURSE_ROSTER.USER_ID WHERE COURSE_ROSTER.COURSE_ID = COURSES.COURSE_ID 推荐答案并非所有数据库供应商(SQL Server、Oracle 等)都以相同的方式实现更新语法...您可以在 SQL Server 中使用联接,但是Oracle 不会喜欢那样的.我相信几乎所有人都会接受相关的子查询
Not all database vendors (SQL Server, Oracle, etc.) Implement Update syntax in the same way... You can use a join in SQL Server, but Oracle will not like that. I believe just about all will accept a correclated subquery however
Update Courses C SET Instructor_ID = (Select User_ID from Course_Roster Where CourseID = C.Course_ID)注意:Course_Roster 中的 User_ID 列最好命名为 InstructorId(或 Instructor_Id)以避免混淆
NOTE: The column User_ID in Course_Roster would probably be better named as InstructorId (or Instructor_Id) to avoid confusion
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