SQL query for user login

Either the following query:

Code:

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INSERT INTO users (login, fullName, email) VALUES ('".$login."', '".$fullName."', '".$email."');

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I'd like to insert the user data if and only if a login with the name foo is not in the table.

I tried:

Code:

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INSERT INTO users (login, fullName, email) VALUES ('".$login."', '".$fullName."', '".$email."') on duplicate key update login='foo';

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But it always gives me a line of registration.

It would not be easier to verify, before the login, that a user already exists in the table. If true then we do nothing, if false, it adds the line.

That's what I did. I built a test first with a select.

An alternative as the login, in my environment, is unique was to be a unique identifier on the field with a login error handling behind.

If you have developed an application in PHP I strongly suggest you phpDoctrine to define a layer of abstraction on top of your database. This allows for example to avoid such problems or you even create your request.