包含数据库完整性

Question

Okay, so this is a straight forward problem but I am having a problem on how I should go about implementing the solution.

So here is what the database structure looks like with much reduced for all that is needed.

The Tables Event, Contact, contact_event_role, event_roles.

create table events(
  event_id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  name VARCHAR(200) NOT NULL,
  PRIMARY KEY(event_id)
);

INSERT INTO events VALUES(1, 'stackoverflow');
INSERT INTO events VALUES(2, 'throwsanerror');

create table contacts(
  contact_id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  fname VARCHAR(40) NOT NULL,
  lname VARCHAR(40) NOT NULL,
  email VARCHAR(90) NOT NULL,
  PRIMARY KEY(contact_id)
);

INSERT INTO contacts VALUES(1, 'bill', 'smith', 'bsmith@email.com');
INSERT INTO contacts VALUES(2, 'amy', 'lee', 'amylee@email.com');

event_roles(
  role_id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  description VARCHAR(80),
  PRIMARY KEY(role_id)
);

//The roles look something like this
INSERT INTO event_roles VALUES(1, 'Event Coordinator');
INSERT INTO event_roles VALUES(2, 'Decision Maker');
INSERT INTO event_roles VALUES(3, 'Inquiry Contact');

contacts_event_role(
  event_id INTEGER UNSIGNED NOT NULL,
  contact_id INTEGER UNSIGNED NOT NULL,
  role_id INTEGER UNSIGNED NOT NULL,
  FOREIGN KEY(event_id) REFERENCES events(event_id),
  FOREIGN KEY(contact_id) REFERENCES contacts(contact_id),
  FOREIGN KEY(role_id) REFERENCES event_roles(role_id),
  PRIMARY KEY(event_id, role_id)
);

INSERT INTO event_role VALUES(1, 1, 1);
INSERT INTO event_role VALUES(1, 1, 2);
INSERT INTO event_role VALUES(2, 2, 1);

So that's the gist of database. With a bit of dummy data. Pretty sure that all is fine and well there.

So here is my logic

What I am trying to do is insert/update the client and role and when necessary have the client fill multiple roles.

So my pseudo code looks like this

//perform a check to see if the event_role is being filled...
check4role = SELECT * FROM contacts_event_role WHERE role_id = 1 AND event_id = 1

//perform a check to see if the contact already exists.
check4contact = SELECT * FROM contacts WHERE fname = :fname AND lname = :lname AND email = :email; 

//if the role is already being filled && contact exists 

if( check4role == true && check4contact == true)
  UPDATE contact_event_role

//else if the role exists and contact does not exists

elseif( check4role == true && check4contact == false)
  INSERT INTO contacts 
  UPDATE contact_event_role

//else if the role does not exists and the contact does exist

elseif( check4role == false && check4contact == true)
  INSERT INTO contact_event_role

//else if the role does not exists and the contact does not exist

elseif( check4role == false && check4contact == false)
  INSERT INTO contacts
  INSERT INTO contact_event_role

You know what I'm not sure but I think I just talked the correct logic out but I would be really interested in some feedback as to if this is how it should be done anyways or if my logic is flawed. I feel like I'm missing something.

THANKS!

Answer 1

It looks good to me - but you could make your code a lot easier to read by changing it to look like this:

if (check4contact == false)
{
    insert into contacts
}

if (check4role == false)
{
    INSERT INTO contact_event_role
}
else
{
    UPDATE contact_event_role
}

I worked this out by breaking it up into two separate checks. Instead of trying to just handle every possible case, I broke up the code into "what are you trying to do" chunks. The first one is just making sure that the contact exists. If they don't, we create them.

Then the second part is updating the contact_event_role table.

You could have also done this by moved out common code - eg, you were calling "INSERT INTO contacts" twice, and both times it was called because "check4contact" was false. So that's one way to clean up your logic.