Newbie Question about customizing Zoho CRM

Newbie Question about customizing Zoho CRM

We are considering Zoho CRM but to work for my company the CRM system would need significant customization, adding a number of new tables, relating fields in the new tables keys in default tables and to keys in other new tables.

Also I am interested in the possibilities of  adding custom code and running custom SQL update and append queries.

Many thanks in advance