Comparing dates (Months) in a IF Statement

Question

I need to compare two dates in Months in Salesforce

Opportunity opp Target targ

If (Month(Opp.closeDate)== Month(targ.Target Date)

{

Add the target Id in Map

}

And the Id will be Queried in SOQL.This is a before Insert trigger on Opp.

Errors : Method does not exist or Incorrect signature :Void Month(Date) /Method does not exist or incorrect signature : void add(Id)from type map.

Can someone please guide me on how to compare date of Opp with Target.

Many Thanks

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Update 1

trigger Updatetraget on Opportunity (after insert,after update) {

Map <Id,Opportunity> mappedopp = new Map <Id,Opportunity>();              {
            
for (Opportunity Opp : Trigger.new)  
            {
                                              
        mappedopp.put(Opp.Monthly_Sales_Target__c,Opp);
    }
    

List <Monthly_Sales_Target__c> msales = [SELECT Id, Name,Target_Month_and_Year__c FROM Monthly_Sales_Target__c where Id in :mappedopp.Keyset()];

    for (Opportunity Opp : Trigger.new)  {

    for (Monthly_Sales_Target__c monthsales : msales)
        
    {
        if(Opp.StageName == 'Closed Won/Completed'&& Opp.CloseDate.Month()==monthsales.Target_Month_and_Year__c.month())
            
        {                
            Opp.Monthly_Sales_Target__c = monthsales.Id;
            
            update Opp;
            }  
    }
}
    

} }

Answer 1

You should use:

If (Opp.closeDate.Month()== targ.Month()){

}