A brief introduction to the database of tyut Taiyuan University of technology in previous years

The brief questions of previous years do not apply to this year , You should also recite the short answer questions in the two question banks in Baidu online disk that I share （ Link to the first blog in the database ）

Chapter one

1． What is the definition of a database ？

         The database is stored in the computer for a long time 、 organized 、 A collection of large amounts of data that can be shared .

2. What are the main functions of database management system

（1） Data definition function ,

（2） Organization of data 、 Storage and management ,

（3） Data manipulation function ,

（4） Transaction management and operation management of database ,

（5） The establishment and maintenance of database ,

（6） Other features .

3． What are the three elements of the data model ？

         data structure 、 Data operation and data integrity constraints constitute the three elements of the data model .

4. What are the data operations in the database ？

         Data operations in the database include inserting 、 modify 、 Delete and query .

5． What are the three types of connections between entities ？

         The connection between entities includes one-to-one connection 、 There are three types of one to many connections and many to many connections .

6． What are the commonly used logical data models in the field of database ？

         The logical data model commonly used in the field of database is hierarchical model 、 Mesh model 、 relational model 、 Object oriented model, etc .

7. What are the components of the database system ？

         A database system consists of a database 、 Database management system 、 Application system and database administrator .

8. Three level structure of database system ？

         The three-level schema structure of database system refers to the external schema 、 Pattern 、 Internal mode

 

9. Database management system

Database management system （Database Management System,DBMS） It is a layer of data management software between the user and the operating system , Provide users or applications with access to the database , Including the establishment of database 、 Inquire about 、 Update and various data control .DBMS Always based on some kind of data , It can be divided into hierarchical models 、 Mesh model 、 relational model 、 Object oriented model, etc DBMS

10. Data independence refers to the mutual independence between applications and data , Unaffected . Data independence is divided into physical data independence and logical data independence .（1） Logical independence ： When the pattern changes , The database administrator modifies the external schema ／ Pattern mapping , Keep the outer mode unchanged , So the application doesn't have to be modified , Ensure the logical independence of data and program , The logical independence of data .（2） Physical independence ： When the storage structure of the database changes , The database administrator modifies the schema ／ Inner pattern mapping , Leave the mode unchanged , Application is not affected . Ensure the physical independence of data and program , Physical independence of data

Chapter two

1. What are the three components of the relational model ？

         The relational model consists of relational data structure 、 Relationship operation and relationship integrity constraints consist of three parts .

2.  The integrity of relational models can be roughly divided into three categories ？

         Constraints on the integrity of relationships include primary key constraints 、 Foreign key constraints and user-defined integrity constraints .

3. Which relational query operations are provided in relational algebra ？

         Queries in relational algebra include the union of Relations 、 hand over 、 Bad 、 Cartesian product 、 choice 、 Projection 、 Operations such as connection and division .

The third chapter

1.SQL What are the commonly used sentences in language ？

        SQL Language set data definitions 、 Data query 、 Data manipulation and data control functions are integrated , Its main operation statements include CREATE、ALTER、DROP、INSERT、UPDATE、DELETE、SELECT、GRANT、REVOKE etc. .

2.SQL Which common aggregation functions are provided in ？ How they are used ？

        SQL Some aggregate functions are provided in , Except for statistical database data , Include COUNT、AVG、SUM、 MAX、MIN etc. , COUNT（*） Beyond usage , Null values are ignored in Statistics , Use DISTINCT Options can be ignored Statistics of duplicate data . Aggregate functions can only be used for SELECT Clause and HAVING Clause .

3. What is a join query ？ How connection queries specify connection conditions ？

         If a query involves two tables at the same time , It is called join query . The connection conditions of connection query can be found in WHERE Clause is specified by a comparison operation , Or in the FROM Clause specifies both the connection method and the connection condition .

4. What is subquery ？ Use in WHERE There are several ways to call subqueries in Clause ？

         Subquery is also called nested query , Is nested in SELECT、INSERT、UPDATE、DELETE And so on Of SELECT Query statement . Use it more often WHERE clause , Use the results of subqueries as search criteria . stay Where There are several ways to use subqueries in Clauses ： from IN Export sub query 、 The subquery is derived from the comparison operator 、 from EXISTS Export sub query .

The fifth chapter

1. What is database integrity ？ What are the types of relational database integrity ？

         Data integrity refers to the logical consistency and correctness of the data in the database .

         The integrity of relational database includes entity integrity 、 Reference integrity and user-defined integrity .

2. The five common constraints are ： Primary key constraint , Foreign key constraints , Non empty constraint , Unique constraint , Check constraint ！

 

Chapter vii.    

1. What aspects of technology and knowledge are involved in database design ？

          Database design involves many aspects of technology and knowledge , Including the basic knowledge of computer 、 Programming methods and skills 、 Principles and methods of software engineering 、 Basic knowledge of databases 、 Knowledge of database design technology and application fields .

2. What are the stages of database design ？

         Database design includes requirements analysis 、 Conceptual structural design 、 Logical structure design 、 Physical structure design 、 There are six stages of database implementation and database operation and maintenance .

3. establish E-R Which steps does the diagram include ？

         establish E-R The process of drawing includes ：（1） First, determine the body shape ,（2） Determine the type of contact ,（3） Put the solid body Combined with connection E-R chart ,（4） Determine the attributes of entity type and connection

 

Fill in the blanks in previous years

1. The database is stored in the computer for a long time , organized , A collection of large amounts of data that can be shared .
2. The functions of the database system include ： Definition of database , Organization, storage and management of database , Database manipulation , Database management and operation management , The establishment and maintenance of database
3. Database manipulation includes inserting , Delete , Modification and query
4. data structure , Data manipulation and integrity constraints constitute the three elements of the data model
5. The practice between entities includes one-on-one contact , One to many connection , Many to many contact
6. The logical data models commonly used in database systems are hierarchical models , Mesh model , relational model , Object oriented model, etc
7.   A database system consists of a database 、 Database management system 、 Application system and database administrator .
8. The three-level schema structure of database system refers to schema 、 Inside mode and outside mode .
9.   Database management system （Database Management System,DBMS） It is located between the user and the operating system

          A layer of data management software , Provide users or applications with access to the database , Including the establishment of database 、

          Inquire about 、 Update and various data control .DBMS Always based on some kind of data , It can be divided into hierarchical models 、 Mesh model 、            relational model 、 Object oriented model, etc DBMS.

10.  Data independence refers to the mutual independence between applications and data , Unaffected . Data independence is divided into physical data independence         And logical data independence .

（1） Logical independence ： When the pattern changes , The database administrator modifies the external schema ／ Pattern mapping , Make external mode             remain unchanged , So the application doesn't have to be modified , Ensure the logical independence of data and program , Abbreviation: Logic of data independence .

（2） Physical independence ： When the storage structure of the database changes , The database administrator modifies the schema ／ Inner pattern mapping , Make the mode secure             Stay the same , Application is not affected . Ensure the physical independence of data and program , Physical independence of data .

11. The relational model consists of relational data structure 、 Relationship operation and relationship integrity constraints consist of three parts .

12. Relationship integrity constraints include primary key constraints 、 Foreign key constraints and user-defined integrity constraints .

13. Queries in relational algebra include the union of Relations 、 hand over 、 Bad 、 Cartesian product 、 choice 、 Projection 、 Operations such as connection and division

14. SQL Language set data query 、 Data manipulation 、 Data definition and data control functions are integrated , Its main operating language

         Sentence includes CREATE、ALTER、DROP、INSERT、UPDATE、DELETE、SELECT、GRANT、

        REVOKE etc. .

15. SQL Some aggregate functions are provided in , Used for statistical database data , Include COUNT、AVG、SUM、MAX、               MIN  etc. , except COUNT（*） Beyond usage , Null values are ignored in Statistics , Use DISTINCT Options can be ignored

         Statistics of duplicate data . The number of aggregated rows can only be used for SELECT Clause and HAVING Clause .

16. If a query involves two tables at the same time , It is called join query . The connection conditions of connection query can be found in WHERE clause         Specify by a comparison operation , Or in the FROM Clause specifies both the connection method and the connection condition .

17. Subquery is also called nested query , Is nested in SELECT、INSERT、UPDATE、DELETE Wait for       SELECT Query statement . Use it more often WHERE clause , Use the results of subqueries as search criteria . stay Where

       There are several ways to use subqueries in Clauses ： from IN Export sub query 、 The subquery is derived from the comparison operator 、 from EXISTS        Export sub query .

18. The security of database means to protect database , Prevent data leakage caused by users' illegal use of the database 、 To alter or destroy .

    The commonly used security control methods in database systems include technology, including user identification and authentication 、 Access control 、 Define views 、 Audit 、 Count      According to encryption .

19. Data integrity refers to the logical consistency and accuracy of the data in the database .

      The integrity of relational database includes entity integrity 、 Reference integrity and user-defined integrity .

20. trigger （Trigger） It is a kind of special event driven stored procedure defined by the user on the relational table . Trigger

      The device consists of inserting the table 、 Modify and delete event activation .

21. Database design includes requirements analysis 、 Conceptual structural design 、 Logical structure design 、 Physical structure design 、 database

       Implementation and database operation and maintenance in six stages .

22. establish E-R The process of drawing includes ：（1） First, determine the body shape ,（2） Determine the type of contact ,（3） Put the solid body

       Combined with connection E-R chart ,（4） Determine the attributes of entity type and connection