Final answer:
A database providing interactive and ad-hoc decision-making support to end-user managers for customer purchases is known as a Data warehouse. It integrates data from various sources for analysis and supports broader decision-making processes, distinct from Data marts, OLTP, or EIS.
Step-by-step explanation:
A database of customer purchases that provides end-user managers with interactive and ad hoc decision-making support is referred to as a Data warehouse. Data warehouses are centralized repositories that store integrated data from multiple sources, which are then used for reporting, data analysis, and supporting decision-making processes. Unlike Data marts, which are subsets of data warehouses tailored for the needs of a specific team or function, data warehouses contain a broader range of company data. They differ from Online Transaction Processing (OLTP) systems, which facilitate and manage transaction-oriented applications typically for data entry and retrieval transaction processing. An Executive Information System (EIS) is a type of decision support system tailored for executive use, usually offering data visualization and easy-to-use interfaces but not specifically focusing on interactive and ad-hoc decision-making support for customer purchases like a data warehouse.