Database Exercises (December 27, 16)--New Ket Network

• Data integrity can be divided into four categories.

1, Entity integrity, the purpose of entity integrity is to ensure that all entities in the database are unique, that is, should not appear exactly the same data records.
2. Zone integrity, matching integrity requires that the data in the data table is within a certain allowable range.
3, the reference integrity, is used to maintain data consistency between the relevant data table means, through the implementation of referential integrity, you can avoid the record changes in one data table resulting in another data table data into an invalid value.
4, user-defined integrity, user-defined by the user according to the actual application of the needs of their own definition.   Title: About data integrity, the following statement is correct? AD

A referential integrity is implemented through a reference relationship between a primary key and a foreign key

B referential integrity is implemented by restricting data types, checking constraints, and so on

C data integrity is achieved through the data controller's own control of the data

D If the information stored in the two tables is interrelated, then as long as one table is modified and the other is modified accordingly, the data in the two tables is said to have integrity

Database Exercises (December 27, 16)--New Ket Network