Apex - 資料庫方法

資料庫類方法是處理DML語句的另一種方式，它比insert、update等DML語句更靈活。

資料庫方法和DML語句的區別

插入操作

透過資料庫方法插入新記錄也很簡單且靈活。讓我們考慮之前的場景，我們使用DML語句插入了新記錄。我們將使用資料庫方法插入相同的記錄。

示例

// 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<apex_invoice__c> InvoiceListToInsert = new List<apex_invoice__c>();
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

現在讓我們使用資料庫方法考慮我們的業務案例示例。假設我們需要更新Invoice物件的status欄位，但同時我們還需要諸如記錄狀態、失敗記錄ID、成功計數等資訊。這無法透過使用DML語句實現，因此我們必須使用資料庫方法來獲取操作的狀態。

示例

如果Invoice的“狀態”為“待處理”且建立日期為今天，我們將更新其“狀態”欄位。

以下程式碼將幫助使用Database.update方法更新Invoice記錄。此外，在執行此程式碼之前，請建立Invoice記錄。

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

// fetch the invoice created today
List<apex_invoice__c> updatedInvoiceList = new List<apex_invoice__c>();
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，我們將僅關注插入和更新操作。其他操作與此類似，與上一章中我們所做的操作類似。