MySQL best approach for db normalising, relationships and foreign keys

Question

There is an username/password verification step first then the database has following structure

^ is primary key

* uses foreign key


1.StudentDetails table
===         


        

Answer 1

It's better to use foreign keys in number format So the Username should be the id of the StudentDetails table.

Can you put the SQL Query that you had tried to run?

Answer 2

option 1:
enter the adress data first, and use that id when createing the row in StudentDetails

option 2:
change the field StudentDetails.Address so its allow NULL valus, enter the StudentDetails, then the adress, and then update the StudentDetails.Address

Answer 3

Ok let me explain you how it would be. I made an example with two tables that you can see below.

Then you can create your query.

mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| addresses      |
| students       |
+----------------+
2 rows in set (0.00 sec)

mysql> select * from students;
+----+----------+-----------+
| id | name     | last_name |
+----+----------+-----------+
|  1 | jhon     | smith     |
|  2 | anderson | neo       |
|  3 | trinity  | jackson   |
+----+----------+-----------+
3 rows in set (0.00 sec)

mysql> select * from addresses;
+----+-----------------+---------+
| id | address         | student |
+----+-----------------+---------+
|  1 | Av 1 2nd Street |       1 |
|  2 | Av 3 4 Street   |       2 |
|  3 | St 23 7 Av      |       3 |
+----+-----------------+---------+
3 rows in set (0.00 sec)

mysql> select s.name,s.last_name,a.address from students s join addresses a on a.student=s.id;
+----------+-----------+-----------------+
| name     | last_name | address         |
+----------+-----------+-----------------+
| jhon     | smith     | Av 1 2nd Street |
| anderson | neo       | Av 3 4 Street   |
| trinity  | jackson   | St 23 7 Av      |
+----------+-----------+-----------------+
3 rows in set (0.00 sec)