custom object: schedule_c fields: Runway_C and date_C Runway_c is a picklist field having track1 and track2 values. date__c field is datetime field.

i having the the records in schedule object e.g airline: kingfisher flight k-101 runway: track1 date: 22-02-2014 11.00 AM

the same records like above...now i created one trigger to prevent the same schedule to insert.i used .adderror to show the validation error while inserting and updating new record.

trigger is working but if i having suppose million of existing records and also want to insert or update the thousands of records, I need to use dynamic soql query...here what i created trigger and soql query...

 trigger newrunway on Schedule__c (before insert, before update) {
 set<DateTime> Date = new set<DateTime>();
 set<id> Runway = new set<id>();

for ( Schedule__c sch : trigger.new){


**string dynamicQuery = 'Select Id,date__c,Runway__c From Schedule__c 
   WHERE     Runway__c  IN :runwayids and  Date__c IN :Dateids';
   List<Schedule__c> schedule = Database.query(dynamicQuery);**

    if (schedule.size() > 0) {
        sch.addError('Flight Already Scheduled on the Runway');


above i created the dynamic query but it seems wrong (problem in logic of query) and need to change...could u help me in this to make it correct

  • THIS CODE MUSN'T WORK. If you need help provide us with acctual code. I don't see your point. Can you edit post and explain why do you need dynamic query? Because as I understand you may need batch job rather than trigger (millions of updates??) Feb 22, 2014 at 9:56
  • hi birthus, i agree with you..i uploaded the sample trigger for better understanding...could you please tell me what i did wrong in query or about wrong logic may be.. pls tell me conceptually or as e.g ...so i will do some changes in it and will check for better soql buildings...
    – user5446
    Feb 22, 2014 at 11:50
  • @user5446, I think where Birthus was confused was where you said 'trigger is working'. He might not have been particularly polite in saying it, but I think that's where he was confused by the question. Feb 22, 2014 at 11:56
  • Sorry for being so rude. I guess I just have bad day ;/ Feb 22, 2014 at 12:31

1 Answer 1


As @Birthus mentioned a trigger will only work for this assuming you have less than 50k records in the DB. You can try to further filter your SOQL, but beyond that Batch may be the way to go.

Assuming that you have less than 50k records, then something like below should work, but will not work should you have a large number of Schedule__c records in the database already

trigger newrunway on Schedule__c (before insert, before update) {

    map<string,set<DateTime>> runway2DateMap = new map<string,set<DateTime>>();

    for(Schedule__c sched : [Select Id, Date__c, Runway__c From Schedule__c Where Date__c > TODAY And Id Not In : trigger.new]){
            runway2DateMap.put(sched.Runway__c, new set<DateTime>());

    for(Schedule__c sched : trigger.new){
            sched.addError('Flight Already Scheduled on the Runway');

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