[judgment question] [short answer question] [Database Principle]

One . Judgment questions

1. The main target of data security is legal users .

right key ： wrong

2. Database recovery is the use of redundant data to rebuild the database .

right key ： Yes

3. The definition of foreign key level cascading is to ensure the consistency of data between related tables .

right key ： Yes

4. Columns that create unique indexes can have some duplicate values .

right key ： wrong

5. The output of a stored procedure can be passed to a variable .

right key ： Yes

6. Writing programs does not belong to the task of the logical structure design stage of the database .

right key ： Yes

7. A rule must be defined once it is used .

right key ： wrong

8. By default , The index created is a nonclustered index .

right key ： Yes

9. Triggers can be called and executed in a program .

right key ： wrong

10.Sa Account can create and delete database roles .

right key ： Yes

11. Because you can insert... Through the view 、 Modify or delete data , So the view is also a real table .

right key ： wrong

12.DELETE Statement just deletes the data in the table , The table itself still exists in the database .

right key ： Yes

13. When each stored procedure executes, it returns an integer return code to the caller . If the value of the return code is not explicitly set , The return code is 0, Indicates that the stored procedure was successfully executed .

right key ： Yes

14. The more indexes you build in the database, the better .

right key ： wrong

15. stay SQL SERVER in , The trigger is executed during data insertion . Update or delete previously executed .

right key ： wrong

16. wildcard “_” Represents a single character .

right key ： Yes

17. Data redundancy is not allowed in the database .

right key ： wrong

18. A table can create multiple foreign keys .

right key ： Yes

19. stay SQL Server In the system , Data information and log information cannot be placed in the same operating system file .

right key ： Yes

20. When using subqueries , Subqueries must be enclosed in parentheses , So as to distinguish external query and sub query .

right key ： Yes

21. A stored procedure is a set of precompiled Transcat-SQL sentence .

right key ： Yes

22. The view itself does not save data , Instead, save a query statement .

right key ： Yes

23.SQL Server Allows users to customize data types .

right key ： Yes

24. The only key is the primary key .

right key ： wrong

25. Columns that set unique constraints can be null .

right key ： Yes

26. Information and data are relative , Sometimes they can be converted to each other .

right key ： Yes

27. The primary key field can be null .

right key ： wrong

28.SQL Server Automatically for primary key Create an index on the constrained column .

right key ： Yes

29.SQL Server The database of can be converted into Access database .

right key ： Yes

30. When deleting a table , Triggers in the table are deleted at the same time .

right key ： Yes

31. stay SQL Server Users in cannot create global variables .

right key ： Yes

32. Only data files can be backed up during database backup .

right key ： wrong

33. Triggers are triggered by events and executed .

right key ： Yes

34. Trigger conflicts with constraint , The trigger will not execute .

right key ： Yes

Two . Short answer

1. What is business ？ What are the characteristics of transactions ？

A transaction is a unit of work executed in a database system , It is a user-defined sequence of operations .
The nature of transactions ： 1） Atomicity 2） Uniformity 3） Isolation, 4） persistence

2. What is data integrity ？ What are the types of data integrity ？

The integrity of the database refers to protecting the correctness of the data in the database 、 Effectiveness and compatibility , Prevent incorrect data from entering the database and causing invalid operations .
Data integrity is divided into the following 4 class ：
（1） Domain integrity
（2） Entity integrity
（3） Referential integrity
（4） User defined integrity

3. What is database backup ？ What are the types of backups ？

Database backup refers to the process that the system administrator periodically or irregularly copies part or all of the contents of the database to another location or another disk to save .
Backup is divided into 4 Kind of :
(1) Full database backup
(2) Differential database backup
(3) Transaction log backup
(4) File and filegroup backup

4. What is stored procedure ？ What are the benefits of using stored procedures ？

Stored procedures are a series of pre edited 、 It can realize specific data operation function SQL Code set , It is associated with a specific database , Stored in SQL Server Server .
Benefits of using stored procedures ：
（1） Enhance the reusability and sharing of code
（2） Reduce network data traffic
（3） Speed up the system
（4） Ensure system security

5. What is a view ？ What are the advantages of using views ？

View is a SELECT The statement specifies , A statement storage definition used to retrieve some row or column data in a database table . essentially , View is actually a SQL Inquire about .
Advantages of using views ：
（1） Query simplification
（2） Protect the security of data in the database
（3） Mask the complexity of the database