PHP scripting to POST to external MySQL for new registrations

OK This is what I have tried

var user_data = {
"Login": params.login,
"MobHeroID" , params.id,
"Email": params.email,
"LastName": params.name,
Password: {
expression: 'MD5("' + params.password + '")'
},
RegDate: {
expression: 'NOW()'
},
UpdateDate: {
expression: 'NOW()'
}
};

var new_user = platform.api.post('MobileHeroDB/Users?fields=MobHeroID,LastName,Email,Login', user_data);

I have made sure that my database has the following fields in the Users table

Login
MobHeroID
Email
LastName
RegDate
UpdateDate
Password

Now using API Docs I registered a new user. To my surprise I got a 200 OK Success but no record was added to the external DB. It is set up as pre_process, so I was surprised at that, as I thought if the MySQL failed at the pre_process stage so would the user registration. Any help most welcome.

Also I am foggy on the MD5 part. Do I need to hold the password twice?...I do not see that as required.

Also if anyone has an example that is done in PHP rather that v8js that would be very helpful too.