Hi,
I am a beginner in database and I'm developing a Database (with Tcl/Tk)
to control the loans of books in a reading room.
I created a table to register the users:
...
db1 eval {CREATE TABLE user (
id_user integer PRIMARY KEY,
name text NOT NULL,
...
id_admin integer NOT NULL
);}
Then create a table for the books:
db1 eval {CREATE TABLE book (
id_book integer PRIMARY KEY,
title text NOT NULL,
...
subject text NOT NULL,
UNIQUE (id_book, title));}
And another table for each copy of the books, because we can have
different copies of a book:
db1 eval {CREATE TABLE copy (
id_copy integer PRIMARY KEY,
id_book integer NOT NULL,
copy_number integer NOT NULL,
...
UNIQUE (id_book, copy_number),
FOREIGN KEY(id_book) REFERENCES book(id_book)
);}
And finally a table to register the loans with many FOREIGN KEYS:
db1 eval {CREATE TABLE loan (
id_loan integer PRIMARY KEY,
id_user integer NOT NULL,
id_book integer NOT NULL,
copy_number integer NOT NULL,
loan_date integer NOT NULL,
devolution_date integer NOT NULL,
...
UNIQUE (id_user, id_book, copy_number,
loan_date),
FOREIGN KEY(id_book, copy_number) REFERENCES
copy(id_book, copy_number),
FOREIGN KEY(id_user) REFERENCES user(id_user),
FOREIGN KEY(id_admin_loan,
id_admin_devolution) REFERENCES user(id_user, id_user));}
But the command to insert a new loan return an error.
The command:
db1 eval "INSERT INTO loan (id_user, id_book, copy_number, loan_date,
devolution_date, ...) VALUES (1, 2, 1, 1532919600, 1514772000, ...)"
The error:
Error: foreign key mismatch - "loan" referencing "user"
foreign key mismatch - "loan" referencing "user"
foreign key mismatch - "loan" referencing "user"
while executing
"db1 eval "INSERT INTO $table_name ($field_list) VALUES ($value_list)""
The insert command works well for insertion into the user, book, and
copy tables.
I'm just having error to insert into the loan table.
I can't find the reason for the error.
Any tip?
Thank you,
Markos
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