cloudbook 14

1. Study summary 1.1 This week summarize your database-related content in the way you like (mind mapping or other). 2. Using database technology your system 2.1 briefly describes how to use the database to transform your system. What table do you want to build? The design of your watch. What are the key classes used in JDBC in the 2.2 system? 2.3 Key code for database related modules. Critical lines need to be annotated. 3. Code volume Statistics 3.1 Statistics the amount of code completed this

Have to spit groove, Ali is really too chaotic, Beijing's written test in the examination room for 2.5 hours, the examination papers are not shipped to the exam room, @ Alibaba Group Campus Recruitment response said: "Beijing students, simple explanation, in order to test the secrecy, printing time is relatively late, the results of an accident." "Still did not test, now the other city's written test is over, a classmate to share the test paper, do it, This set of questions do not know which cit

--Create a databaseCreate DATABASE hq20161114Go--Using the databaseUse hq20161114Go--Create student tablesCREATE TABLE Xuesheng(code int,Name varchar (10),Sex char (10),Chengji Decimal (18,2))--Add student informationINSERT into Xuesheng values (1001, ' One ', ' male ', 11)INSERT into Xuesheng values (1002, ' two ', ' Male ', 22)INSERT into Xuesheng values (1003, ' three ', ' female ', 33)INSERT into Xuesheng values (1004, ' four ', ' female ', 44)Go--Querying dataSELECT * FROM Xuesheng--Query d

[[emailprotected] ~]# /etc/init.d/mysql start #后续服务直接启动即可[[emailprotected] ~]# /etc/init.d/mysql start? 5) Testing? Operate the database on any one node, synchronize operations with other nodes, and if the same record is in operation, only one node operation succeeds.? 6) View work statusMariaDB [(none)]> SHOW VARIABLES LIKE 'wsrep_%'\GMariaDB [(none)]> SHOW STATUS LIKE 'wsrep_%'\GMariaDB [(none)]> SHOW STATUS LIKE 'wsrep_cluster_size';+--------------------+-------+| Variable_name | Value |

INDEXGen_clust_index of TABLE' Test '. ' Citynew ' Trx ID35489574Lock_mode X Waiting*** (2) TRANSACTION: TRANSACTION 35489577, ACTIVE8SEC startingINDEX READ, thread declared inside INNODB theMySQL TABLESinch Use 1, Locked14LOCK struct (s), HEAP size1136,3ROW LOCK (s) MySQL thread ID2634624, OS thread handle139887388956416, QUERY ID109768953 172.168.18.202RootStatistics--dead Lock SELECT * fromCityWHEREcity_id=103 for UPDATE***(2) holds the LOCK (S):RECORD LOCKSSPACEId479Page NO3N Bits the IN

as querying a document with the name "Joe" and an ID of 1:>db.post.find ({"Name": "Joe"}) { "_id" :objectid (" 54a530c3ff0df3732bac1681 ")," id ":2," name ":" Joe "," Age ":30, "Sex" :1, "school" : "Marry" }{ "_id" NBSP;: objectid ("54a530c3ff0df3732bac1680"), "id" :1, "name" : "Joe", "age" :30, "Comments" :[ "Test2", "Test9", "test5" ], "Sex" :1, "School" : "Marry" }>db.post.find ({"Name" : "Joe", "id": 1}) { "_id" :objectid ("54a530c3ff0df3732bac1680"), "id ":1," name ":" Joe "," age ":30,"

" --either group, or aggregate. SelectCommodities,SUMAmount asTotal Amount,AVGAmount asaverage amount,MAXAmount asMaximum amount,MINAmount asMinimum Amount fromDataGroup byCommodity--grouping and performing aggregations---grouping statistics --====================== grouping filter ============================ --count the total sales of orders of up to 100 per department SelectSales department,SUMAmount asTotal Sales fromDataGroup bySales DepartmentSelectSales department,SUMAmount asTotal S

to use this method, there is a premise that the data in the corresponding field in the table is not duplicated, that is, the uniqueness is guaranteed.PRIMARY KEY constraintPRIMARY KEY constraint, that is, the data in the character corresponding to the primary key is not allowed to repeat, and if repeated, the data operation (mainly increment and change) fails . -- 主键约束（冲突）测试 insert into my_pri3 values(‘MATH00123‘,‘泛函分析‘); insert into my_pri3 values(‘MATH00123‘,‘非线性分析‘); 1 2 3

to False$mysqli->query ("INSERT into Test values"), $mysqli Rollback ();//ROLLBACK TRANSACTION, 100 no Insert $mysqli->query ("INSERT into test values (101)"), $mysqli->commit (),//COMMIT TRANSACTION, insert only 1017. Meta-Data metadataMetadata is used to describe the columns in the result set, and metadata information can be obtained through the Mysqli_result interface.$res = $mysqli->query ("SELECT * from Test"); Var_dump ($res->fetch_fields ());650) this.width=650; "Src=" Http://s4.51cto.co

The 14th Chapter distributed database systemDistributed database is composed of a set of data distributed in the computer network of different computers, each node in the network has the ability to handle independently (called site autonomy), can perform local applications. At the same time, each node can also perform global applications through the network subsystem.Characteristics:Data independence (in a centralized database system, data independence consists of two aspects: the logical indepe

Com.example.demo; Import Com.example.demo.service.UserService; Import Org.junit.Test; Import Org.junit.runner.RunWith; Import org.springframework.beans.factory.annotation.Autowired; Import Org.springframework.boot.test.context.SpringBootTest; Import Org.springframework.test.context.junit4.SpringRunner; Import java.util.Date; @RunWith (springrunner.class) @SpringBootTest public class Springboot3applicationtests { @Autowired private UserService UserService; @Test public Void Register () { St

', ' demo.txt ', ' R '); Loop Utl_file.get_line (inputfile, input); Dbms_output.put_line (input); End Loop; --Close File Utl_file.fclose (Inputfile); exception When No_data_found then Dbms_output.put_line (' End of File! ');End--Writing filesDeclare Inputfile Utl_file.file_type; --File Object Input VARCHAR2: = ' Hello world! ';Begin --Specify file --3 parameters are: Folder file open mode [R (Read) W (write

other changes(4) You can make a soft link to the directory　　Usage Scenario: Hard Link: Data backup4. Search for files in the file system(1) Locate find data in locate database, locate data need to be refreshed manually　　Touch File1cd/tmp/The newly created file, which is not written to the locate database, requires a manual update of the database UpdateDB　　UpdateDBFind/tmp-name File2Find/-USESR StudentFind/-type LFind/-perm 777Find/-size +100mFind/-mmin 30Find/-exec Execute next commandFind/-use

default_message_loglevel (usually kern_warning).3. Log level of the console (Console_loglevel)When the message level specified by PRINTK is less than the specified console log level, the contents of the message are displayed on the console. The log level of the console is defined in the Include/linux/kernel.h file, which defaults to Default_console_loglevel (the value equals 7), which means that by default, PRINTK () is higher than the kern_debug level The message content can be displayed on th

judgment may be related to this. The information on the Internet indicates that it is possible that the xserver-xorg was deleted by mistake.Workaround:Reinstall the Xserver-xorg software.Because at this time can not be logged into the system through Xwindow, and can not be switched to the console via CTRL+ALT+F1, etc., can only be powered off after the USB stick boot.(1) in the U disk system, the problem of the Ubuntu system first set to boot to the console.sudo mount-t ext4/dev/xxxx/media/xxxx

understood by anyone with Windows experience. The soft link itself is a file, but this file does not hold data, it holds a link, and points to other files.The methods you create are similar to hard links:The discovery is one more option-s means that this is a soft link.By ls-l we find that the file type of the soft link is L, which means that the soft link is not a regular file but a symbolic link file. The symbolic link file has its own dentry, with its own inode, but the data domain holds ano

extended partition is not used directly, and is used in logical partitioning, so the extended partition can be divided into logical partitions. Their relationship is a contained relationship, and all logical partitions are part of the extended partition. In Linux, the first hard disk partition is HDA partition, the primary partition number is hda1-4, and the logical partition starts from 5.Capacity of the hard disk = capacity of primary partition + capacity of extended partitionCapacity of

Tags: cat view file Contents commandTouch Create File commandMV Move File commandThe current directory is equivalent to changing the file nameCommands related to text documentsCat View the contents of a file commandTAC flashback to view the contents of the fileCAT/ETC/PASSWD >>/tmp/1.txt Append passwd file contents to 1.txt fileMan cat view usage and parameters of CAT commandsMore split screen display file contentsWC View the number of rows in a file command7th Day of the Linux CentOS study (Jun

The previous Process Control 2, describes the zombie process, and the solution of the two kinds of 4. Add two more below.How to resolve:3: Ignore SIGCHLD signalParent process settings Ignore SIGCHLD signal, child process end automatically frees process table resourceIgnore SIGCHLD signal:Signal (SIGCHLD, sig_ign)4: Capture SIGCHLD SignalThe parent process captures the SIGCHLD signal and executes the wait () in the Capture function codeHandling SIGCHLD Signals:void Pfun (int nsignal)Signal (Sigch

) After the installation is complete, select SQL Server Management Studio in the program, the following interface appears, you can use Windows default login, you can also use the SA user, Password to log in to the password you previously set.(12) After successful login, the following interface will appearThis completes the database installation.2. Configuring the TCP service portIn the taskbar, click Start , point to All Programs , clickMicrosoft SQL Server SQL Server2008, configure tools, and t