Upsert list with values of another list

Question

I have 2 lists, they show the ForecastingQuota of my users for Quarter 1 and Quarter 2. I want to copy all the values of Quarter 1 to Quarter 2 if I choose the quarter on the SelectList (just copy the quota Amount of the user). How can I achieve this?

<apex:outputText>Copy Quarter</apex:outputText>
<apex:selectList value="{!selectedQuarterToCopy}"  size="1">
    <apex:selectOptions value="{!QuarterList}" />
</apex:selectList>
<apex:outputText>To this Quarter</apex:outputText>
<apex:selectList value="{!selectedQuarterCopied}"  size="1">
    <apex:selectOptions value="{!QuarterList}" />
</apex:selectList>

<apex:commandButton value="Copy Quarter to Quarter" action="{!copyQuarterToQuarter}" styleClass="buttonCopyQuota" reRender="null" />

List<ForecastingQuota> queryQuotaListQ1 = [SELECT Id, QuotaAmount, QuotaOwnerId, QuotaOwner.UserRole.Name, StartDate FROM ForecastingQuota WHERE ForecastingTypeId = :forecastTypeList.get(0).Id AND StartDate >=:selectedQuarterQ1 AND StartDate <:selectedQuarterQ2 AND QuotaOwnerId IN : userIdSet ORDER BY QuotaOwnerId ASC];
List<ForecastingQuota> queryQuotaListQ2 = [SELECT Id, QuotaAmount, QuotaOwnerId, QuotaOwner.UserRole.Name, StartDate FROM ForecastingQuota WHERE ForecastingTypeId = :forecastTypeList.get(0).Id AND StartDate >=:selectedQuarterQ2 AND StartDate <:selectedQuarterQ3 AND QuotaOwnerId IN : userIdSet ORDER BY QuotaOwnerId ASC];

Answer 1

I second the idea of cloning and looping through. So basically you would do something like

 // get start date of next quarter
startOfQuarter = [Select startDAte From Period Where type = 'Quarter' and StartDate = THIS_FISCAL_QUARTER].startdate; 
startofQuarter = startOfQuarter + 100; 
startOfQuarter = startOfQuarter.toStartOfMonth();

List<ForecastingQuota> queryQuotaListQ1 = [SELECT Id, QuotaAmount, QuotaOwnerId, QuotaOwner.UserRole.Name, StartDate FROM ForecastingQuota WHERE ForecastingTypeId = :forecastTypeList.get(0).Id AND StartDate >=:selectedQuarterQ1 AND StartDate <:selectedQuarterQ2 AND QuotaOwnerId IN : userIdSet ORDER BY QuotaOwnerId ASC];
List<ForecastingQuota> queryQuotaListQ2 = new List<ForecastingQuota> queryQuotaListQ2();
for(ForecastingQuota forecast: queryQuotaListQ1) {
    ForecastingQuota newForecast = forecast.clone(false, false, false, false);
    newForecast.startDate = startOfQuarter;
    queryQuotaListQ2.add(newForecast);

}
insert queryQuotaListQ2

;