Hello Team,

I want to share basic dml functionality on sales-force objects, I hope this will help you all. 

Regards,

Manoj Jain 

Page Code:
<apex:page controller="todayDML">
    <script type="text/javascript">
        function saveAlert()
        {
            alert("record has been saved successfully");
            setTimeout("location.reload(true);");
        }
        function deleteAlert()
        {
            alert("record has been deleted successfully");
            setTimeout("location.reload(true);");
        }
        function modifyAlert()
        {
            alert("record has been modified successfully");
            setTimeout("location.reload(true);");
        }
        function removeAllAlert()
        {
            alert("All record has been deleted successfully");
            setTimeout("location.reload(true);");
        }
        
       
    </script>
<apex:messages /> 
    <apex:form >
        <apex:panelGrid columns="2">
            Name: <apex:inputText value="{!dName}" />
            Last Name: <apex:inputText value="{!lName}"/>
            Summary: <apex:inputText value="{!sum}"/>
        </apex:panelGrid>
        <br/><br/>
        <apex:commandButton value="Save" action="{!save}"  oncomplete="saveAlert()" />
        <apex:commandButton value="Update" action="{!updateDml2}" oncomplete="modifyAlert();"/>
        <apex:commandButton value="Delete" action="{!delete1}" oncomplete="deleteAlert();"/>
        <apex:commandButton value="Remove All" action="{!removeAll}" oncomplete="removeAllAlert();"/>
        <apex:commandButton value="Search" action="{!doSearch}" rerender="block1" status="status"/>
        <apex:commandButton value="Reset" action="{!reset}"/><br/><br/>
    </apex:form>    
    <apex:form >
        <apex:pageBlock id="block1">
            <apex:actionStatus id="status" startText="requesting..."/>
                <apex:pageBlockTable value="{!dataDml}" var="da" rendered="{!NOT(ISNULL(dataDml))}">
                    <apex:column value="{!da.name}"/>
                    <apex:column value="{!da.Last_Name__c}"/>
                    <apex:column value="{!da.Other__c}"/>
                    <apex:column value="{!da.dml1__r.name}"/>
                    <apex:column value="{!da.dml1__r.Summary__c}"/>
                </apex:pageBlockTable>
        </apex:pageBlock>
    </apex:form>
        </apex:page>

Controller Code:

public class todayDML 
{
    public String dName{get; set;}
    public String lName{get; set;}
    public String sum{get; set;}
    public String valueOne{get; set;}
    
    public void save()
    {
        dml1__c d1 = new dml1__c(
            name = dName,
            Summary__c = sum
        );
        insert d1;
        
        dml2__c d2 = new dml2__c(
            name = dName,
            Last_Name__c = lName,
            Other__c = sum,
            dml1__c = d1.id
        );
        insert d2;
        //ApexPages.addMessage(new ApexPages.message(ApexPages.severity.INFO,'Bill-To Sites successfully created'));

       
    }
    public void updateDml2()
    {
        List<dml2__c> d2 = [SELECT id,name, Last_Name__c, Other__c,dml1__c FROM dml2__c WHERE name =: dName];
        List<dml1__c> d1 = [SELECT Id, Summary__c FROM dml1__c];
        for(dml2__c dm2 : d2)
        {
            dm2.Last_Name__c = lName;
            dm2.Other__c = sum;
            for(dml1__c dm1 : d1)
            {
               if(dm1.Id == dm2.dml1__c)dm1.Summary__c = sum;
            }
        }
        update d2;
        update d1;
       
    }
    public void delete1()
    {
        dml1__c[] d1 = [select name from dml1__c where name =: dName limit 50];
        dml2__c[] d2 = [select name from dml2__c where name =: dName limit 50];
        try {
            delete d1;
            delete d2;} 
        catch (DmlException e){
            System.debug(e);}
            
    }
    
    public void removeAll()
    {
        dml1__c[] d1 = [select name from dml1__c];
        dml2__c[] d2 = [select name from dml2__c];
        try {
            delete d1;
            delete d2;} 
        catch (DmlException e){
            System.debug(e);}
            
    }
    
   List<dml2__c> dataDml;
    public List<dml2__c> getDataDml(){
        return dataDml;
    }
   public PageReference doSearch(){
        dataDml = [select name, Last_Name__c, Other__c,dml1__r.name, dml1__r.Summary__c from dml2__c where name =: dName];
        return null;
    }
    
    public void reset(){
        dName = '';
        lName = '';
        sum = '';
    }
    
}