Tattoo_Artists
| ArtistID | Name | Age | ExperienceLevel |
| 1 | Alice | 30 | Intermediate |
| 2 | Bob | 28 | Advanced |
| 3 | Carol | 45 | Expert |
| 4 | Dave | 67 | Beginner |
| 5 | Eve | 19 | Novice |
Piercers
| PiercerID | Name | Age | YearsOfExperience |
| 1 | Frank | 30 | 10 |
| 2 | Grace | 29 | 5 |
| 3 | Harry | 35 | 15 |
| 4 | Ivy | 40 | 20 |
| 5 | Jack | 47 | 8 |
Customers
| CustomerID | Name | Age | PreferredServiceType |
| 1 | Mary | 30 | Tattoo |
| 2 | John | 28 | Piercing |
| 3 | Anna | 45 | Tattoo |
| 4 | Ben | 19 | Piercing |
| 5 | Chris | 67 | Tattoo |
Appointments
| AppointmentID | ServiceDate | ServiceType | TattooArtistID | PiercerID | CustomerID |
| | | (→ Tattoo_Artists.ArtistID) | (→ Piercers.PiercerID) | (→ Customers.CustomerID) |
| 1 | 2022-01-01 10:00:00 | Tattoo | 1 | 1 | 1 |
| 2 | 2022-01-01 11:00:00 | Piercing | None | 1 | 2 |
| 3 | 2022-01-02 10:00:00 | Tattoo | 2 | 2 | 3 |
| 4 | 2022-01-02 11:00:00 | Piercing | 3 | 3 | 4 |
| 5 | 2022-01-03 10:00:00 | Tattoo | 4 | 4 | 5 |