MySQL delete duplicate records but keep latest

Question

I have unique id and email fields. Emails get duplicated. I only want to keep one Email address of all the duplicates but with the latest id<

Answer 1

I must say that the optimized version is one sweet, elegant piece of code, and it works like a charm even when the comparison is performed on a DATETIME column. This is what I used in my script, where I was searching for the latest contract end date for each EmployeeID:

DELETE CurrentContractData
  FROM CurrentContractData
  INNER JOIN (
    SELECT
      EmployeeID,
      PeriodofPerformanceStartDate,
      max(PeriodofPerformanceEndDate) as lastDate,
      ContractID
    FROM CurrentContractData
    GROUP BY EmployeeID
    HAVING COUNT(*) > 1) Duplicate on Duplicate.EmployeeID = CurrentContractData.EmployeeID
    WHERE CurrentContractData.PeriodofPerformanceEndDate < Duplicate.lastDate;

Many thanks!