TShirt : sam55 Store : "Tom's DryGoods" Store : "Tom's DryGoods" City : "Salt Lake City" State : "UT"What will happen if we change the example to contain only the TShirt data:
TShirt : sam60 Store : "Tom's DryGoods"As expected the database software creates the TShirt "sam60" with its ?Store field filled in with "Tom's DryGoods". However, filling in the ?Store field is tantamount to claiming that a Store object with this name exists. If this is true--if "Tom's DryGoods" was entered sometime earlier--then the effect is that ACEDB establishes the link between the TShirt and the Store.
However, suppose there is no preexisting Store object called "Tom's DryGoods". In this case ACEDB satisfies the implicit claim by creating the object. Thus,
if you establish a link, ACEDB guarantees that the object being linked to exists. ACEDB may satisfy the guarantee by creating the object de novo.When de novo creation occurs, the result is an empty object, meaning that nothing is known about it other than its name. In the previous example "Tom's DryGoods" will be visible in the Store selection list and the "sam55" text window (but no longer in boldface), it no longer represents an active link and cannot be opened. This makes sense because a user would learn nothing new by following the link.
Empty objects are not presented to users by ACEDB unless they are referred to by other objects. Since "sam60" refers to "Tom's DryGoods", this store will persist in the database. If we removed the reference to "Tom's DryGoods" from "sam60", "Tom's DryGoods" would no longer be seen in any context by the user.
Now consider this data entered in isolation:
Store : "JCPenny's"Since there is no other information about "JCPenny's", and nothing else refers to it, entering this data does not create a visible object. It does not even appear in the selection list.
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