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6. DATABASES
Databases are used to store various types of information in a manufacturing enterprise. For example, consider an inventory tracking system. A simple database might contain a simple list of purchased parts. Each part is a line in a database table, as shown in figure X.1. If a new inventory item is added, a new row is added to the table. If parts are added or removed to the inventory, the quantity value for one of the rows is changed. The total inventory cost can be calculated by multiplying the quantity and part costs together, and summing these for all rows. The tables are often designed to suit the way a particular business runs.
Figure X.1 - A Simple Inventory Table
A more complex database will be made up of many tables that relate items together. For example a more complex database might have separate tables for customer data, supplier data, purchased inventory, work in process, finished inventory, etc. The purchased inventory table might refer to a supplier number that identifies a supplier in the supplier table. The formal name for a database that uses related tables of information is 'relational'.
In modern applications a database (server) will run on one computer, but be shared by many other computers (clients) that access it through networks. Client programs might be highly variable. For example a worker on the shop floor may only be able to view order information. A shop floor supervisor might be able to change order status, personnel tables. A salesperson might be able to enter new orders, and check on order status. It is also possible to access the database directly and make special inquiries using a special command language called Structured Query Language (SQL).
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