Not getting column of table - mysql

Question

CREATE TABLE login(
name varchar(200),
email varchar(200) primary key,
count int,
depart varchar(200),
type varchar(1),
password varchar(40));
CREATE TABLE qsstudent(
department varchar(200),
qs int,
email varchar(200),
type varchar(1),
qscorrect int,
qsdone int,
qswrong int ,
FOREIGN KEY (email) REFERENCES login(email));
CREATE TABLE qsteacher(
email varchar(200),
department varchar(200),
qsentered int,
type varchar(1),
FOREIGN KEY (email) REFERENCES login(email));
When I run the query below, it cannot find the login.depart column. I have tried doing this several times but it is not running. I don't think that there is an error in the foreign key
SELECT qsteacher.qsentered
FROM login,qsteacher
WHERE login.depart=qsteacher.department
AND qsstudent.email=login.email;
but still the error persists.

Answer 1

cannot find the login.depart column
This is the exact thing your query can't find:
SELECT qsteacher.qsentered
FROM login,qsteacher
WHERE login.depart=qsteacher.department
AND qsstudent.email=login.email; //<-- you didn't select qsstudent
If you want to use qsstudent on this query you need add it to the FROM
FROM login,qsteacher,qsstudent
I recommend to do something like this with INNER JOIN:
SELECT T3.qsentered
FROM login as T1
INNER JOIN qsstudent as T2 on T2.email=T1.email
INNER JOIN qsteacher as T3 on T1.depart=T3.department
and If you want to select by specific user just add this WHERE to the end:
WHERE T1.email = 'user_email'

Answer 2

Firstly your primary key should be an id, not an email, for multiple reasons, like uniqueness and index. So I will add an id to all of your tables which should auto increment with every record. And Your foreign key should be an id as well so I will change that.
CREATE TABLE login(
id int NOT NULL AUTO_INCREMENT primary key,
name varchar(200),
email varchar(200),
count int,
depart varchar(200),
type varchar(1),
password varchar(40));
CREATE TABLE qsstudent(
id int NOT NULL AUTO_INCREMENT primary key,
department varchar(200),
qs int,
email varchar(200),
type varchar(1),
qscorrect int,
qsdone int,
qswrong int ,
FOREIGN KEY (login_id) REFERENCES login(id));
CREATE TABLE qsteacher(
id int NOT NULL AUTO_INCREMENT primary key,
email varchar(200),
department varchar(200),
qsentered int,
type varchar(1),
FOREIGN KEY (login_id) REFERENCES login(id));
Now for the query that you are trying to run from what I can tell:
SELECT q.qsentered FROM qsteacher q
JOIN login l ON l.id = q.login_id
JOIN qsstudent s ON s.login_id = l.id
WHERE s.department = q.department
Please comment exactly what it is you are trying to query so I can better answer your question. It is not clear what you are looking for.