I am designing data base for inventory management system which is used by nearly 10 to 15 companies. This database contains nearly 25 tables.
Is it reliable to use a shared schema architecture, with each schema corresponding to a company and all schemas in a single database?
If I read your question, you are suggesting that each company has its own schema. This means two things:
Better you should develop one schema for the entire database; each table would have a field called 'CompanyID' which naturally would define to which company each row belongs. This field would be a foreign key to the Companies table.