我写的关于salsforce.com的第一个Trigger

Trigger:
trigger oppStageTrigger on Opportunities(before insert,before update)
{
 if(Trigger.isBefore)
 {
  if(Trigger.isUpdate||Trigger.isinsert)
  { 
   List<Product_Forecast_c> PFList=new List<Product_Forecast_c>();
   //Defines a Product_Forecast_c list with no elements
   //Determine the distinct opportunities entries
   Set<ID> pbeIds=new Set<ID>();
   for(OpportunityLineItem oli:Trigger.new)
      pbeIds.add(oli.product_forcastid);
    //Get the specific record of Opportunities
   Map<Id,Opportunities> opportunityMap=new Map<Id,Opportunities>
   (
     //Return stage value
     [select stagename from Opportunities where id in :pbeIds]
   );     
   string oppName=[select name from opportunities where id in:pbeIds].name;
   //Get the records of product@forcast by opportunities's name   
   for(Product_forecast_c PFC:[select spansion_part_c from product_forecast_c where opportunity_c=:oppName])
   {
    PFList.add(PFC.spansion_part_c);
   }    
   //string[] partnum=[select spansion_part_c from product_forecast_c where opportunity_c=:oppName];
   for(OpportunityLineItem oli:Trigger.new)
     string stagevalue=opportunities.get(oli.OpportunitiesId).stageName;
   for(integer i=0;i<PFList.size();i++)
      { 
       if(stagevalue=='Reference Design Win'||stagevalue=='Design Win'||stagevalue=='Closed PO/Production')
       { 
        integer PFID=[select product_forecast_cid from product_forecast_c where opportunity_c=:oppName].product_forecast_cid;
        if(PFList.get(i)==null)
        {
               for(OpportunityLineItem oli:Trigger.new)
               {
                oli.addError('Spansion Part Number is required on all Product & Forecast items
                       when setting the Stage to this value.  Please enter Spansion Part Number
                       by clicking Edit next to the item(s) in the Product & Forecast section.');
               }                  
           }      
           else if(PFID==null)
           {
               for(OpportunityLineItem oli:Trigger.new)
               {
                oli.addError('A Product & Forecast item (with Spansion Part Number) is required w
                       hen setting the Stage to this value.  Please create a Product & Forecast
                        entry by clicking the "New" button in that section.');
               }
           }
           else
           {
            switch(i)
            {
             case 0:
             { 
              // oli.spansion_part_no_1_c is the first spansion_part_# which is needed to show
              oli.spansion_part_no_1_c=PFList.get(0);
              break; 
             }
             case 1:
             {
              // oli.spansion_part_no_2_c is the first spansion_part_# which is needed to show
               oli.spansion_part_no_2_c=PFList.get(1);
              break;
             }
            }
           }
          }
          else
          {           
           switch(i)
            {
             case 0:
             { 
              // oli.spansion_part_no_1_c is the first spansion_part_# which is needed to show
               oli.spansion_part_no_1_c=PFList.get(0);
              break; 
             }
             case 1:
             {
              // oli.spansion_part_no_2_c is the first spansion_part_# which is needed to show
               oli.spansion_part_no_2_c=PFList.get(1);
              break;
             }
            }
          }
        }      
  }
 }
}
这个trigger有些语法问题，经过修改后的代码如下（修改这个的过程真的很痛苦，因为我对它语法不是很熟悉）：

trigger oppStageTrigger on Opportunity(before update)
{
if(Trigger.isBefore)
{
if(Trigger.isUpdate)
{
integer j=0;
Map<Integer,String> m=new Map<Integer,String>();
Set<String> pbeIds=new Set<String>(); 

for(Opportunity oli:Trigger.old) pbeIds.add(oli.Name);

String oppName=[select name from Opportunity where Name in:pbeIds].name;
integer PFID=[select count() from Product_Forecast__c where Opportunity__r.name=:oppName];

 //Set<ID> pbeIds=new Set<ID>(); 
//for(Opportunity oli:Trigger.old)
// pbeIds.add(oli.id); 
//String oppName=[select name from Opportunity where id in:pbeIds].name;Opportunity名称可以重复,故改用id来获取唯一的记录
String oppName=Trigger.old[0].name;用这条语句可以很快地获取name,而不必去再次查询了（系统出错时才发现这便捷的方法，当初学习真失败！！）。

if(PFID==0)
{
if(Trigger.new[0].StageName=='Reference Design Win'||Trigger.new[0].StageName=='Design Win'||Trigger.new[0].StageName=='Closed PO/Production')
{
Trigger.new[0].addError('A Product & Forecast item (with Spansion Part Number) is required w hen setting the Stage to this value. Please create a Product & Forecast entry by clicking the "New" button in that section.');
}
}
try
{
for(Product_Forecast__c PFC:[select Spansion_part__c from Product_Forecast__c where opportunity__r.name=:oppName])
{
m.put(j,PFC.Spansion_part__c);
j++;
}
}
catch(QueryException e)
{
system.debug(e);
}
for(integer i=0;i<m.size();i++)
{
if(Trigger.new[0].StageName=='Reference Design Win'||Trigger.new[0].StageName=='Design Win'||Trigger.new[0].StageName=='Closed PO/Production')
{
if(m.get(i)==null)
{
Trigger.new[0].addError('Spansion Part Number is required on all Product & Forecast items when setting the Stage to this value. Please enter Spansion Part Number by clicking Edit next to the item(s) in the Product & Forecast section.');
}
else
{
if(i==0)
{
for(Opportunity oli:Trigger.new)
{
//spansion_part_no_1_c is the first spansion_part_# which is needed to show
oli.spansion_part_no_1__c=m.get(0); break;
}
}
else if(i==1)
{
for(Opportunity oli:Trigger.new)
{
//spansion_part_no_2_c is the first spansion_part_# which is needed to show
oli.spansion_part_no_2__c=m.get(1); break;
}
}
}
}
else
{
if(i==0)
{
for(Opportunity oli:Trigger.new)
{
//spansion_part_no_1_c is the first spansion_part_# which is needed to show
oli.spansion_part_no_1__c=m.get(0); break;
}
}
else if(i==1)
{
for(Opportunity oli:Trigger.new)
{
//spansion_part_no_2_c is the first spansion_part_# which is needed to show
oli.spansion_part_no_2__c=m.get(1); break;
}
}
}
}
}
}
}