Apex - 数据库方法

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

数据库方法和DML语句之间的差异

INSERT插入操作

通过数据库方法插入新记录也非常简单和灵活。 让我们采用前面的场景，其中我们使用DML语句插入了新的记录。 我们将插入相同的使用数据库方法。

例如：

//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());
	}
}
}

UPDATE更新操作

让我们来看看使用数据库方法的业务案例示例。 假设我们想更新Invoice对象的状态字段，但是同时，我们希望有诸如记录状态，失败的记录ID，成功计数等信息。这是不可能通过使用DML语句完成的，因此我们必须使用数据库方法来获取我们操作的状态。

例如：

//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());
	}
}
}