[Database Principle and Application Tutorial (4th Edition | wechat Edition) Chen Zhibo] [Chapter 7 exercises]

One 、 choice question

1	2	3	4	5	6	7	8	9	10
B	C	B	D	A

1． stay SQL Server What is not an object in is （ ）.

A） user
B） data
C） surface
D） data type

2． Variable declared ：DECLARE @i int,@c char(4), For now @i assignment 10, by @c assignment ’abcd’, Correct language
The sentence is （ ）.

A）SET @i=10, @c=‘abcd’
B）SET @i=10, SET @c=‘abcd’
C）SELECT @i=10, @c=‘abcd’
D）SELECT @i=10, SELECT @c=‘abcd’

3． stay SQL Server Server , A stored procedure is a set of predefined and （ ） Of Transact-SQL sentence .

A） preservation
B） compile
C） explain
D） To write

4． It can be used （ ） To declare a cursor .

A）CREATE CURSOR
B）ALTER CURSOR
C）SET CURSOR
D）DECLARE CURSOR

5． When the 【】 The positions are BREAK,CONTINUE or RETURN when , The output value is （ ）.

DECLARE @n int 
SET @n=3 
WHILE @n>0 
    BEGIN 
        SET @n=@n-1 
        IF @n=1 []
    END 
PRINT @n

A）1,0, No output
B）1,1,_
C）0,0,0
D）0,1,2

Two 、 Completion

1．Transact-SQL Can be used in local variable and Global variables Two variables .

2． stay Transact-SQL Two types of annotators can be used in ： Single-line comments - - And multiline comments /… …/.

3． The command used to declare one or more local variables is DECLARE.

4． Whether stored procedures or triggers , All are SQL Statement and Process control Collection of statements .

5．SQL Server 2012 Support DML trigger 、DDL trigger and Login trigger There are three types of triggers .（ For reference only ）

6． Each trigger has Insert table and Delete table Two special tables are in the database .

7． stay SQL Server 2012 There is Database backup 、 Transaction log backup 、 Differential backup and File and filegroup backup Four types of backup .

8． stay SQL Server 2012 There is Simple reduction 、 complete reduction and Batch log restore Three database restore modes .

9． The backup device can be Hard disk 、 Magnetic tape or The Conduit .

3、 ... and 、 Short answer

1． What is trigger ？ What are the functions of triggers ？

• Trigger is a special stored procedure , It contains a series of T-SQL sentence , But its execution is not with EXECUTE The command explicitly calls , It is automatically activated and executed when certain conditions are met , Such as inserting records into the table ﹑ It is automatically activated and executed by the system when updating records or deleting records .

• Using triggers has the following advantages :
  （1） Triggers are automatically activated and executed when an event occurs . Such as , After an object is defined in the database , Or it will be activated and automatically executed immediately after making some modifications to the data in the table .
  （2） Triggers can achieve more complex integrity requirements than constraints , such as CHECK Columns in other tables cannot be referenced in constraints , Triggers can reference ;CHECK Constraints are just conditional expressions connected by logical symbols , Unable to complete complex logical judgment function .
  （3） The trigger can modify the status before and after according to the table data , Take corresponding measures according to their differences .
  （4） Triggers can prevent malicious or erroneous INSERT、UPDATE and DELETE operation .

2． Brief description SQL Server 2012 Data backup in 4 Types .

• （1） Full database backup
  Full database backup （Database Backup） It refers to backing up all objects in the database , Including transaction logs .
  This backup type requires relatively large storage space to store backup files , The backup time is also long , When restoring data , Just restore a backup file .

• （2） Differential backup
  Database differential backup （Differential Database Backup） It's a complement to a full backup , Only back up the database since the last time
  After a full backup （ Be careful ： Not after the last differential backup ） Part of the database changes . Compared with full backup , The data volume of differential backup is smaller than that of full backup , Backups are also faster than full backups . therefore , Differential backup is usually used as a common backup method .

• （3） Transaction log backup .
  Transaction log backup （Transaction Log Backup） Only the transaction log contents of the database are backed up . Transaction log backup takes transaction log files as backup objects , It is equivalent to recording every operation in the database .
  The transaction log records the database changes in a certain period of time , So before doing a transaction log backup , Must enter
  Row full backup . Similar to differential backup , Transaction log backups produce smaller files 、 Short occupation time , But when restoring data ,

• （4） File and filegroup backup
  File and filegroup backup is to backup a single database file or filegroup , Its advantage is convenience and flexibility ,
  And when restoring, you can restore only the damaged database files .

3．SQL Server What methods are provided to reduce the execution time of backup or restore operations .

• （1） Use multiple backup devices to perform backup processing at the same time . Empathy , You can restore databases from multiple backup devices at the same time .
• （2） Comprehensive use of database full backup 、 Differential backup or transaction log backup to reduce the amount of data that needs to be backed up each time .
• （3） Use file or filegroup backups and transaction log backups , In this way, only those files containing relevant data can be backed up or restored , Not the entire database .

PS： For reference only , Because of limited personal ability , If there is a mistake , Please grant me your advice ~

Reference

Tutorial of database principle and application part 4 Reference answers to exercises in version / Wendouding @lh2468lh