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SQL Error 150

The code here has the error:

/* SQL Error (1005): Can't create table 'university.advisor' (errno: 150)  Foreign key constraint is incorrectly formed */

but I can't understand how to address it. I tried to use "index" and this didn't seem to be relevant. Can you tell me what I'm missing?
drop database if exists University;
create database University;
use University;

create table department(
dept_name varchar(20),
building  varchar(15),
budget    numeric(12, 2),
check (budget > 0),
index(dept_name),
primary key(dept_name)
);

create table instructor(

id varchar(20),
name varchar(20) not null,
dept_name varchar(20),
salary numeric(8, 2),
foreign key(dept_name) references department(dept_name)
    on delete set null,
primary key(id)
#index(id)
);



create table course(

course_id varchar(8),
title varchar(50),
dept_name varchar(20),
credits numeric(2,0),
check (credits > 0), 
foreign key(dept_name) references department(dept_name)
    on delete set null,
primary key(course_id)

);

create table classroom(

building varchar(15),
room_number varchar(7),
capacity numeric(4, 0),
primary key(building,room_number),
index(building), #new index
index(room_number) #new index
);


create table section(

course_id varchar(8),
sec_id varchar(8),
semester varchar(6),
year numeric(4,0),
building varchar(15),
room_number varchar(7),
time_slot_id varchar(4),

foreign key(course_id) references course(course_id)
    on delete cascade,
foreign key(building) references classroom(building)
    on delete set null,
foreign key(room_number) references classroom(room_number)
    on delete set null,
primary key(course_id,sec_id,semester,year),
#index(building),
#index(room_number),
index(course_id), #new index # doees it have anything to do with the indices?
index(sec_id), #new index
index(semester), #new index
index(year) #new index
);

create table teaches(

id varchar(20),
course_id varchar(8),
sec_id varchar(8),
semester varchar(6),
year numeric(4,0),


foreign key(course_id) references section(course_id) #department(sec_id) -> section(sec_id)
    on delete cascade,
foreign key(sec_id) references section(sec_id) #department(sec_id) -> section(sec_id)
    on delete cascade,
foreign key(semester) references section(semester) #department(sec_id) -> section(sec_id)
    on delete cascade,
foreign key(year) references section(year)
    on delete cascade,
foreign key(id) references instructor(id)
    on delete cascade,
primary key(id,course_id,sec_id,semester,year)
);



create table advisor(

s_id varchar(5),
i_id varchar(5),

foreign key(i_id) references instructor(id)
    on delete set null,

foreign key(s_id) references student(id)
    on delete cascade,

primary key(s_id)
#index(s_id)
);

create table student(

id varchar(5),
name varchar(20) not null,
dept_name varchar(20),
tot_cred numeric(3,0),

foreign key(dept_name) references department(dept_name)
    on delete set null,
#primary key(id),
index(id) #new index

);

create table takes(

id varchar(5),
course_id varchar(8),
sec_id varchar(8),
semester varchar(6),
year numeric(4,0),
grade varchar(2),

    foreign key(course_id) references section(course_id)
        on delete cascade,

    foreign key(sec_id) references section(sec_id)
        on delete cascade,

    foreign key(semester) references section(semester)
        on delete cascade,

    foreign key(year) references section(year) #section(year) -> section(year)
        on delete cascade,

    foreign key(id) references student(id)
        on delete cascade,

    primary key(id,course_id,sec_id,semester,year)

);

create table prereq(

course_id varchar(8),
prereq_id varchar(8),


    foreign key(course_id) references course(course_id)
        on delete cascade,

    foreign key(prereq_id) references course(course_id),

    primary key(course_id,prereq_id)

);

create table timeslot(

time_slot_id varchar(5),
day2 varchar(1),
start_hr int,
start_min int,
end_hr int,
end_min int,

primary key(time_slot_id,day2,start_hr,start_min)	                                 	        	
);

load data infile 'j:/department.txt' into table department fields terminated by ',';
load data infile 'j:/course.txt' into table course fields terminated by ',';
load data infile 'j:/classroom.txt' into table classroom fields terminated by ',';
load data infile 'j:/section.txt' into table section fields terminated by ',';
load data infile 'j:/instructor.txt' into table instructor fields terminated by ',';
load data infile 'j:/teaches.txt' into table teaches fields terminated by ',';
load data infile 'j:/student.txt' into table student fields terminated by ',';
load data infile 'j:/advisor.txt' into table advisor fields terminated by ',';
load data infile 'j:/takes.txt' into table takes fields terminated by ',';
load data infile 'j:/prereq.txt' into table prereq fields terminated by ',';
load data infile 'j:/timeSlot.txt' into table timeSlot fields terminated by ',';

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University.zip
0
JCW2
Asked:
JCW2
  • 5
  • 4
6 Solutions
 
derekkrommCommented:
You're trying to create a FK on student, but student hasn't been created yet. Move the advisors create below the student create.
0
 
JCW2Author Commented:
Okay, now I'm getting

/* SQL Error (1452): Cannot add or update a child row: a foreign key constraint fails (`university`.`advisor`, CONSTRAINT `advisor_ibfk_2` FOREIGN KEY (`s_id`) REFERENCES `student` (`id`) ON DELETE CASCADE) */

How do I interpret and deal with that?
0
 
arnoldCommented:
You have to adjust the loading of data to match the constrains that you have.
As derekkromm pointed out with the create directive, you need to load the advisor table data prior to the student one.
0
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derekkrommCommented:
Right - put the loads in the same order as your creates to ensure you aren't violating your own FKs
0
 
JCW2Author Commented:
Placing the load statement for "advisor" before "student" doesn't seem to do anything.

(It looked like Derekkromm was talking about moving the create statements, above the load statements.)
0
 
derekkrommCommented:
I was, but all of your loads should be in the same order as your creates since that is the logical progression of the tables.

All of the table creates themselves work if you remove the loads, right?
0
 
JCW2Author Commented:
I have the orders the same now. I am however getting the same error:

/* SQL Error (1452): Cannot add or update a child row: a foreign key constraint fails (`university`.`advisor`, CONSTRAINT `advisor_ibfk_2` FOREIGN KEY (`s_id`) REFERENCES `student` (`id`) ON DELETE CASCADE) */
0
 
derekkrommCommented:
you must have some data in your advisor file that contains student ids that don't exist in the student table
0
 
derekkrommCommented:
if you want to test, i'd suggest removing that FK, inserting the data, and then running a query similar to:

select * from advisor where s_id not in (select s_id from student) to get a list of student ids that are in advisor but not student
0
 
JCW2Author Commented:
Thank you for your help.
0

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