Question

Two tables:

COURSE_ROSTER – contains

• COURSE_ID as foreign key to COURSES
• USER_ID as field I need to insert into COURSES

COURSES – contains

• COURSE_ID as primary key
• INSTRUCTOR_ID as field that needs to be updated with USER_ID field from COURSE_ROSTER

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 

Answer 1

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) 

NOTE: The column User_ID in Course_Roster would probably be better named as InstructorId (or Instructor_Id) to avoid confusion