Create Query for Retrieve CRM data from Entity and UPDATE another Entity

Following example shows how to get data from CRM DB and update another Entity with current data:

QueryExpression query = Session.CreateQuery("ld_entity1");

query.Criteria.AddCondition("column_for_condition1",ConditionOperator.Equal,value_for_conditon);

query.Criteria.AddCondition("column_for_condition2", ConditionOperator.Null);

query.Criteria.AddCondition("column_for_condition3",ConditionOperator.NotEqual,0);

query.ColumnSet = new ColumnSet( new string[] { "column_to_get1", "column_to_get2" });

EntityCollection entities = Session.RetrieveEntityCollection(query);

foreach (Entity entityToUpdate in workOrderEntities.Entities)
{                    
   EntityToUpdate enToUpdate= new EntityToUpdate();

   enToUpdate.ld_workorderId = (Guid)entityToUpdate["column_with_value"];

   enToUpdate.ld_garageentryid = new EntityReference("column_with_value", 

                                                     (Guid)garageEntry.ld_garageentryId);

   enToUpdate.ld_garage=garageEntryEntity.GetAttributeValue<EntityReference>("column_with_value");

   Session.Update(enToUpdate);
}

public EntityCollection RetrieveEntityCollection(QueryExpression query)
{
    return Service.RetrieveMultiple(query);
}

public QueryExpression CreateQuery(string entityName, bool allColumn = true)
{
    if (entityName == null || entityName == string.Empty)
        return null;
 
    QueryExpression query = new QueryExpression(entityName);
    query.ColumnSet = new ColumnSet(allColumn);
    return query;
}