In response to finecur <finecur@xxxxxxxxx>: > On Sep 10, 9:55 pm, finecur <fine...@xxxxxxxxx> wrote: > > Hi > > > > Here is my table: > > > > Table School > > ( > > id integer, > > name text > > ); > > > > Table Department > > ( > > id integer, > > school_id integer reference school(id), > > name text > > ); > > > > Table Course > > ( > > department_id integer references department(id), > > name text, > > course_number text > > ) > > > > I would like to make the course_number unique, but not in the course > > table, nor in department. I would like to make the course_number > > unique in the scope of School. So, you may see the same course_number > > in Course table, but (school_id, course_number) should be always > > unique. How can I make the constrain? ALTER TABLE Course PRIMARY KEY(school_id, course_number); and add the school_id column to the Course table. -- Bill Moran http://www.potentialtech.com ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
