📌  相关文章
📜  Apex-数据库方法

📅  最后修改于: 2020-11-05 03:15:06             🧑  作者: Mango

数据库类方法是使用DML语句的另一种方式，它比DML语句(如插入，更新等)更灵活。

数据库方法和DML语句之间的差异

DML Statements Database Methods
Partial Update is not allowed. For example, if you have 20 records in list, then either all the records will be updated or none. Partial update is allowed. You can specify the Parameter in Database method as true or false, true to allow the partial update and false for not allowing the same.
You cannot get the list of success and failed records. You can get the list of success and failed records as we have seen in the example.
Example − insert listName Example − Database.insert(listName, False), where false indicate that partial update is not allowed.

插入操作

通过数据库方法插入新记录也非常简单和灵活。让我们考虑一下以前的场景，其中我们使用DML语句插入了新记录。我们将使用数据库方法插入相同的内容。

例

// Insert Operation Using Database methods
// Insert Customer Records First using simple DML Statement. This Customer Record will be
// used when we will create Invoice Records
APEX_Customer__c objCust = new APEX_Customer__C();
objCust.Name = 'Test';
insert objCust; // Inserting the Customer Records

// Insert Operation Using Database methods
APEX_Invoice__c objNewInvoice = new APEX_Invoice__c();
List InvoiceListToInsert = new List();
objNewInvoice.APEX_Status__c = 'Pending';
objNewInvoice.APEX_Customer__c = objCust.id;
objNewInvoice.APEX_Amount_Paid__c = 1000;
InvoiceListToInsert.add(objNewInvoice);
Database.SaveResult[] srList = Database.insert(InvoiceListToInsert, false);

// Database method to insert the records in List
// Iterate through each returned result by the method

for (Database.SaveResult sr : srList) {
   if (sr.isSuccess()) {
      // This condition will be executed for successful records and will fetch the ids 
      // of successful records
      System.debug('Successfully inserted Invoice. Invoice ID: ' + sr.getId());
      // Get the invoice id of inserted Account
   } else {
      // This condition will be executed for failed records
      for(Database.Error objErr : sr.getErrors()) {
         System.debug('The following error has occurred.');
         
         // Printing error message in Debug log
         System.debug(objErr.getStatusCode() + ': ' + objErr.getMessage());
         System.debug('Invoice oject field which are affected by the error:' 
            + objErr.getFields());
      }
   }
}

更新操作

现在让我们考虑使用数据库方法的业务案例示例。假设我们需要更新Invoice对象的status字段，但是同时，我们还需要记录状态，失败记录id，成功计数等信息。这无法通过使用DML语句来实现，因此我们必须使用Database方法获得我们的运营状态。

例

如果发票的状态为“待处理”且创建日期为今天，我们将更新发票的“状态”字段。

下面给出的代码将有助于使用Database.update方法更新发票记录。另外，在执行此代码之前，请创建一个发票记录。

// Code to update the records using the Database methods
List invoiceList = [SELECT id, Name, APEX_Status__c,
   createdDate FROM APEX_Invoice__c WHERE createdDate = today];

// fetch the invoice created today
List updatedInvoiceList = new List();
for (APEX_Invoice__c objInvoice: invoiceList) {
   if (objInvoice.APEX_Status__c == 'Pending') {
      objInvoice.APEX_Status__c = 'Paid';
      updatedInvoiceList.add(objInvoice);    //Adding records to the list
   }
}

Database.SaveResult[] srList = Database.update(updatedInvoiceList, false);
// Database method to update the records in List

// Iterate through each returned result by the method
for (Database.SaveResult sr : srList) {
   if (sr.isSuccess()) {
      // This condition will be executed for successful records and will fetch
      // the ids of successful records
      System.debug('Successfully updated Invoice. Invoice ID is : ' + sr.getId());
   } else {
      // This condition will be executed for failed records
      for(Database.Error objErr : sr.getErrors()) {
         System.debug('The following error has occurred.');
         
         // Printing error message in Debug log
         System.debug(objErr.getStatusCode() + ': ' + objErr.getMessage());
         System.debug('Invoice oject field which are affected by the error:' 
            + objErr.getFields());
      }
   }
}

在本教程中，我们将仅关注插入和更新操作。其他操作与这些操作以及我们在上一章所做的操作非常相似。