Goal: 'Bulkify' the existing Apex trigger used for counting how many dupes a Lead had, and inserting the Contact Id of the Contact record (if more than one, the first in the list) that matched the email address of the Lead.

Here's a snippet of the code I want to bulkify:

for (Lead l : Trigger.new) {
        //Make sure our lead has an email address
        if (l.Email != null) {
            //Find a dupe
            String leadEmail = l.Email;
            List<Lead> dupeLeads = [SELECT Id FROM Lead WHERE Email = :leadEmail];

            //If a dupe is found, update a field
            if (dupeLeads.size() > 0) {
                l.Dupe_Lead_Counter__c = dupeLeads.size();
            } else {
                //0 would designate a true unique
                l.Dupe_Lead_Counter__c = 0;

So, this is clearly violating the mandate of 'No SOQL queries in For() loops.'

Reading the various doucmentation and tutorials, it looks as though the pattern needs to be a List of the sObjects we want to query from (all Leads with email values in this case) and then use mapping to somehow map the lists of dupe Leads (by email) with the master Lead email list.

How do I even group duplicate emails into a List without creating a For() loop/SOQL query in the first place?

This is what I have so far:

Set<String> leadsWithEmails = new Set<String>();
    for (Lead l : Trigger.new) {
        if(l.email != null) {
    //Query for all Leads
    List<Lead> potentialDupeLeads = [SELECT Id,Email FROM Lead
                                    WHERE Email IN :leadsWithEmails];

    //Step 3: Make a map that lets you search for Leads by Email
    Map<String, Lead> emailToLeadMap = new Map<String, Lead>();
    for (Lead l : potentialDupeLeads) {
        emailToLeadMap.put(l.Email, l);
  • 1
    @AdrianLarson testing it thanks! Btw, when you created the Set<String> lead Emails, why is there a z in new Set<z String>();
    – GPP
    Jul 3, 2016 at 16:27
  • 1
    Mobile formatting ftw.
    – Adrian Larson
    Jul 3, 2016 at 17:29
  • @AdrianLarson just clarifying-- is that z intentional?
    – GPP
    Jul 3, 2016 at 20:48
  • @AdrianLarson good stuff, I am encountering an error: Invalid foreign key relationship this statement is tripping it up: record.Lead.Dupe_Lead_Counter__c = count;
    – GPP
    Jul 4, 2016 at 3:41
  • 1
    Did the updated answer resolve?
    – Adrian Larson
    Jul 12, 2016 at 14:25

1 Answer 1


You can use aggregate queries for this.

Set<String> leadEmails = new Set<String>();
for (Lead record : trigger.new)

Map<String, Integer> emailCounts = new Map<String, Integer>();
for (AggregateResult aggregate : [
    SELECT Email, count(Id) records
    FROM Lead WHERE Email IN :leadEmails
    GROUP BY Email
    emailCounts.put((String)aggregate.get('Email'), (Integer)aggregate.get('records'));

for (Lead record : trigger.new)
    Integer count = emailCounts.containsKey(record.Email) ?
        emailCounts.get(record.Email) : 0;
    record.Dupe_Lead_Counter__c = count;
  • thanks! Sorry for belated reply, just to be clear-- you created this code to augment my starting point, or is there original code I have that needs to be stripped? Trying to track with your additions
    – GPP
    Jun 13, 2016 at 23:24
  • 1
    @GPP This would replace what you have entirely. Note that the counts above do not include the leads from the transaction itself, which you probably also want to count. Not that you are updating those matching records...
    – Adrian Larson
    Jun 13, 2016 at 23:30
  • thanks for the quick reply (pretty sure that's a world record!) So I would effectively wrap this snippet of code in my Lead Trigger code, correct? 'trigger CountDupeLeads on Lead (before insert, before update) {}'
    – GPP
    Jun 13, 2016 at 23:33
  • 1
    @GPP Yeah you would wrap it in that. FYI you can in-line format code with ` characters.
    – Adrian Larson
    Jun 13, 2016 at 23:44
  • 1
    Oh yeah I can add that but just build a set.
    – Adrian Larson
    Jun 14, 2016 at 0:17

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