1, each China local resident and his unique ID number.

2. There is only one monitor in each class, and each monitor only serves the only class.

Second, an example of a one-to-many relationship:

1. There are many parallel classes in a grade, and many parallel classes belong to a grade.

2. How many students are there in a class, and how many students belong to a class?

3. Examples of many-to-many relationships:

1, a class has several teachers, and a teacher can also take several classes.

2. There are several students taking a class at the same time, and one student can take multiple classes at the same time.

Detailed explanation

The above one-to-one, one-to-many and many-to-many relationships all belong to mapping. In mathematics, mapping is a term that refers to the "corresponding" relationship between two groups of elements, and it is a noun. "Mapping" or "projection" needs to define the function of projection law in advance before operation. Therefore, "mapping" calculation can realize cross-dimensional correspondence.

The corresponding calculus belongs to pure digital calculation, which cannot realize cross-dimensional correspondence, and differential simulation can realize complex simulation of this dimension. Mapping can approximate unrelated sets, while calculus can only perform accurate operations in large sets that are continuously related.