I am developing a website which is fully dynamic. If I load metas and other information of the website from database, will it affect my website's SEO?
Search engines bots see your final HTML (after the server delivery of your page to the client web browser). Therefore, you can build and customize your pages like you want.
Otherwise, it depends on what you modify compared to the old version of your site. If you modify good SEO spots like
<h2>, etc., your SEO can be impacted but if you use the same content as the old version, there wouldn't be any repercussion for your website's SEO.
There is no impact to SEO whether meta information is static HTML or dynamically generated HTML. By the time the search engines see it there is no difference - they look at the meta content itself and not the technology behind it.
If managing the meta information in a database helps you to ensure it is kept relevant, up-to-date and accurate then obviously in time this will generate a positive impact.
If your database queries are horrendously inefficient and the page loading time is increased significantly that can have a negative SEO impact, but this isn't usually a problem.