public class DataTableController {

    @AuraEnabled
    public static List<Opportunity> getOpportunities()
    {
        List<Opportunity> oppList=new List<Opportunity>();
        
        oppList=[select Name,Account.Name,StageName,CloseDate,Amount from Opportunity
                 where Amount != NULL];
        
        return oppList;
    }
    
    @AuraEnabled
    public static void updateOpportunities(List<Opportunity> oppsList){
        try
        {
            Database.update(oppsList);
            
          }
        catch(Exception ex)
        {
            system.debug(ex.getMessage());
        }
    }
}

<aura:component implements="force:appHostable,force:hasRecordId,flexipage:availableForAllPageTypes" 
                controller="DataTableController"
                access="global">
	
        <!-- Three important parts of datatable is Key , data and columns
         so we need attribute for data and columns(metatadata)-->
    <!-- attributes -->
    <aura:attribute name="data" 
                    type="Object"/>
    
    <aura:attribute name="columns" 
                    type="List"/>
    
<aura:attribute name="updatedRecord" type="Object[]" />

    <!-- handlers-->
    <aura:handler name="init" 
                  value="{!this}" 
                  action="{!c.doInit}"/>
    
    <lightning:card title="OpportunityDatatable">
        
        <lightning:datatable aura:id="opportunitydatatable"
                             keyField="id"
                             data="{!v.data}"
                             columns="{!v.columns}"
                             onsave="{!c.handleSaveOpps}"
                             hideCheckboxColumn="true"/>
        
</lightning:card>
    
    {!updatedRecord}

</aura:component>

({
	doInit : function(component, event, helper) {
        
        helper.queryColumns(component,event,helper);
        
        helper.queryContacts(component,event,helper);
  	},
    
    handleSaveOpps: function (component, event, helper) {
        debugger;    
        var draftValues = event.getParam('draftValues');
console.log(draftValues);
        var action = component.get('c.updateOpportunities');
        action.setParams({ 
            "oppsList": draftValues
        });
        action.setCallback(this, $A.getCallback(function(response) {
            var state = response.getState();
            if (state === "SUCCESS") {
                helper.fireSuccessToast(component);  
                helper.fireRefreshEvt(component);
            } else if (state === "ERROR") {
                var errors = response.getError();
                console.error(errors);
                helper.fireFailureToast(component);  
            }
        }));
        $A.enqueueAction(action);
    }
     
})


({
	queryColumns : function(component,event,helper) {
        
		  component.set('v.columns', [
            {label: 'Opp Name', fieldName: 'Name', editable : 'true', type: 'text'},
            {label: 'Acc Name', fieldName: 'AccountName', type: 'text'},
            {label: 'StageName', fieldName: 'StageName', type: 'text'},
            {label: 'CloseDate', fieldName: 'CloseDate', type: 'date'},
            {label: 'Amount', fieldName: 'Amount', type: 'currency', cellAttributes: { alignment: 'left' }} 
        ]);
	},
    
    queryContacts : function(component,event,helper) {
        
        var action=component.get('c.getOpportunities');
        
        action.setParams({
        });
        action.setCallback(this, function(response){
            var state = response.getState();
            if (state === "SUCCESS") {
                
                  //the following code will display the parent account name
                 var rows = response.getReturnValue();
                 for (var i = 0; i < rows.length; i++) {
                    var row = rows[i];
                    if (row.Account) row.AccountName = row.Account.Name;
                }
                //component.set("v.data", response.getReturnValue());
                 component.set("v.data", rows);
            }
        });
        $A.enqueueAction(action);
    },
    
     fireSuccessToast : function(component) {
        var toastEvent = $A.get("e.force:showToast");
        toastEvent.setParams({ 
            'title' : 'Success', 
            'message' : 'Opportunities updated sucessfully.' ,
            'type':'success'
        }); 
        toastEvent.fire(); 
    },
    
    fireFailureToast : function(component) {
        var toastEvent = $A.get("e.force:showToast");
        toastEvent.setParams({ 
            'title' : 'Failed', 
            'message' : 'An error occurred. Please contact your administrator.',
            'type':'error'
        }); 
        toastEvent.fire(); 
    },
    
    fireRefreshEvt : function(component) {
        var refreshEvent = $A.get("e.force:refreshView");
        if(refreshEvent){
            refreshEvent.fire();
        }
    }
       
})