Requirements: The database will maintain records for each company, including a unique company ID$,$ name, email address, phone number, website, and type. Companies employ customers, and for each customer, the database will store a unique customer ID$,$ address $($if applicable$),$ phone number, email, first name, last name, and type. In addition, a customer can have relationships with other customers $($note: some customers may not report any relationships with others$).$ A company must have at least one employed customer but can have multiple customers, while a customer may be employed by no company or one company. Customers can request quotes for units; however, before doing so$,$ they mush schedule a consultation by appointment. A customer may schedule one or multiple consultants, each identified by a unique consultation ID$,$ date$/$time$,$ and address. Each consultation involves a single designer, with their unique ID$,$ name, email address, and phone number recorded. Designers may participate in multiple consultations, although some may not be involved in any. Once customers request quotes for units, the database will track details such as the unique quote ID$,$ issue date, total amount, tax amount, and whether the quote was accepted. If a discount applies, the discount amount will also be recorded. Additionally, any comments on a quote will be stored as a note. Each quote must be requested by exactly one customer. A quote includes units with specified color, location, and quantity. Note that each quote must include at least one unit, and while a unit can appear in multiple quotes, some units may not be included in any quotes yet. For each unit, the database will track its unique ID$,$ name, and price. Once a customer requests a quote, and it is approved, installations can be scheduled. The database will record the unique installation ID$,$ date and time, and address. A single quote may require multiple installations, but some quotes may not require any installation. However, each installation must be associated with exactly one quote. Installations are performed by installers, and the database will record their first name, last name, phone number, and email address. An installation may involve one or multiple installers, and each installer may perform multiple installations. The database will also track installers who have not yet performed any installations.