DML&Database Methods

*****************执行操作过程中的错误信息的收集以及操作******************************************

// Create a list of contacts
List<Contact> conList = new List<Contact> {
        new Contact(FirstName='Joe',LastName='Smith',Department='Finance'),
        new Contact(FirstName='Kathy',LastName='Smith',Department='Technology'),
        new Contact(FirstName='Caroline',LastName='Roth',Department='Finance'),
        new Contact()};
            
// Bulk insert all contacts with one DML call
Database.SaveResult[] srList = Database.insert(conList, false);
//SaveResult这个数组中存放的是每一个插入操作之后系统返回的信息
// Iterate through each returned result
for (Database.SaveResult sr : srList) {
    if (sr.isSuccess()) {
        // Operation was successful, so get the ID of the record that was processed
        System.debug('Successfully inserted contact. Contact ID: ' + sr.getId());
    } else {
        // Operation failed, so get all errors
        for(Database.Error err : sr.getErrors()) {
            System.debug('The following error has occurred.');
            System.debug(err.getStatusCode() + ': ' + err.getMessage());
            System.debug('Contact fields that affected this error: ' + err.getFields());
	 }
    }
}



*****************************父对象中选择子对象*****************************************************************

SELECT Id,name,(select Phone from contacts) FROM Account WHERE Name='Test Trigger2'


*****************************子对象中选择父对象*************************************************************** 
SELECT Id,Account.Id,Account.Industry from Contact where Phone='111222333'


*****************************利用 SobjectType 来确定要查询的对象*************************************************
 public static RecordType rd = [select Id,Name from RecordType where DeveloperName='BG' and SobjectType='Project_Publicity__c'];
 
 
 
 
 *************************** Bad Way 不要在for 循环中使用DML语句，很容易达到governor limits****************************
 public with sharing class AccountHandler {
    public static void CreateNewOpportunity(List<Account> accts) {
        for (Account a : accts) {
            Opportunity opp = new Opportunity();
            opp.Name = a.Name + ' Opportunity';
            opp.AccountId = a.Id;
            opp.StageName = 'Prospecting';
            opp.CloseDate = System.Today().addMonths(1);
            insert opp;
        }
    }
}

**************************** Good Way ******************************************************************************
***************************因为系统可以一次性处理200条数据，所以要充分利用这个特性***************************************
public with sharing class AccountHandler {
    public static void CreateNewOpportunity(List<Account> accts) {
        List<Opportunity> opps = new List<Opportunity>();
        for (Account a : accts) {
            Opportunity opp = new Opportunity();
            opp.Name = a.Name + ' Opportunity';
            opp.AccountId = a.Id;
            opp.StageName = 'Prospecting';
            opp.CloseDate = System.Today().addMonths(1);
            opps.add(opp);
        }
        if (opps.size() > 0) {
            insert opps;
        }
    }
}