Please note that all relationships with this element, and all its children will be deleted as well.
What does this mean?
Parent, Children and Cascade deletions
"Children" elements are elements that directly depend on another object (the "parent").
They only have sense in a certain context, and if the context to which they belong is removed, to mantain data meaning and integrity the application provides also the removal of them (now become "orphans").
Example
Take the case of a Travel and of the Events occurred during it.
In this example, deleting a Travel will leave all of its Events meaningless since, taken alone, they would have no context in which to place themselves, nor a way to reach them.
Consequently, the removal of a Travel also causes the elimination - cascading - of all Events that occurred in that Trip.
Important
Note that this operation is not limited to one level of relationship, but proceeds with children of deleted children and so on, until the entire database is freed from unnecessary data.
This lets the user remove all data about a Travel by simply deleting that Travel.
Georg Forster describes the experiment conducted by his father (Johann Reinold) and Mr. Wales (the ship's astronomer) who wanted to measure the temperature of water. The two find themselves in a difficult situation as they are unable to reach the ship again until they hear the ringing of a bell that allows them to approach and then board the Adventure.
Text on source
They rowed about for some time, making vain efforts to be heard, but all was silent about them, and they could not see the length of their boat. They were the more unfortunate, as they had neither maft nor fail, and only two oars. In this dreadful suspence they determined to lie still, hoping that, provided they preserved their place, the floops would not drive out of fight, as it was calm. At last they heard the jingling of a bell at a distance; this found was heavenly music to their ears; they immediately rowed towards it, and by continual hailing, were at last answered from the Adventure, and hurried on board, overjoyed to have escaped the danger of perishing by slow degrees, through the inclemencies of wheter and through famine.
English translation
Folios/Pages
pp. 99-100
Date
1772 12 14 circa
Observations on the events description
The dots on the map indicate the places where sound and music events were described. They don't represent travel stages.