I am moving an existing application which is currently having an oracle db to salesforce. What are the possible ways for data migration? Which will be the most efficient and why?

I have my UI on salesforce. I want a piece of code to execute on some server. How this can be  achieved?

Hi,I am new to salesforce. Wanted to know that, is there any functionality in SOQL that can work similar to "NVL" functionality in SQl? 

I have my UI on salesforce. I want a piece of code to execute on some server. How this can be  achieved?

Hi,I am new to salesforce. Wanted to know that, is there any functionality in SOQL that can work similar to "NVL" functionality in SQl? 

I am getting error message while solving this challenge in Trailhead :

To complete this challenge, add a validation rule which will block the insertion of a contact if the contact is related to an account and has a mailing postal code (which has the API Name MailingPostalCode) different from the account's shipping postal code (which has the API Name ShippingPostalCode).Name the validation rule 'Contact must be in Account ZIP Code'.
A contact with a MailingPostalCode that has an account and does not match the associated Account ShippingPostalCode should return with a validation error and not be inserted.
The validation rule should ONLY apply to contact records with an associated account. Contact records with no associated parent account can be added with any MailingPostalCode value. (Hint: you can use the ISBLANK function for this check)

Error Message is :  There was an unhandled exception. Please reference ID: HKIZNLVZ. Error: Trailhead::TrailheadTimeOut. Message: Trailhead.view: failed to get a 200 response. Made 3 attempts each resulting in a 403 or 500 failure for url challenges?key=%5B%22trailhead.challenge.validation_rules.en.us.192%22%5D.

I am not sure what went wrong here.
My Validation Rule is on Contact Object  :

  AND ( NOT(ISBLANK( Account.Name)),
( MailingPostalCode <> Account.ShippingPostalCode))

Can anyone please help with this.

How do I check if a valid Contact is returned from a query like this in Apex.

 

Contact o = [SELECT c.Id, Email, LastName, FirstName, MailingCity, HomePhone, MailingState, MailingStreet, MailingPostalCode, AccountId, Source_Code__c, Drupal_User_Id__c FROM Contact c WHERE c.Email = :n.Email AND c.Id != :n.Id limit 1];

 

How do I check to see if o is a populate Contact object.