Tags: blog use problem div code HTML Management logTo manage the job training information, establish 3 tables:S (S#,SN,SD,SA) S#,sn,sd,sa respectively represents the student number, the student name, the unit, the Student Age C (C#,CN) C#,CN respectively represents the course number, the course name SC (s#,c#,g) S#,c#,g respectively represents the student number, the elective course number, the study result 1. Use standard SQL nested statements to qu
. Generally, programmers can only consider a limited number of possibilities.(4) The optimizer includes many complex optimization technologies that can be mastered only by the best programmers. Automatic system optimization is equivalent to making everyone have these optimization technologies.
RDBMS calculates the execution cost of various query execution policies based on a certain cost model, and then selects the execution scheme with the minimum cost.Centralized databaseThe execution overhead
Question 1
Problem description:
Create three tables to manage job business training information:
S (s #, Sn, SD, SA) s #, Sn, SD, and SA represent the student ID, Student name, organization, and student age respectively.
C (C #, CN) C #, CN represents the course number and Course name respectively.
SC (s #, C #, g) s #, C #, and G represent Student IDs, elective course numbers, and academic scores respectively.
1. Use standard SQL nested statements to
S_c database is built.
(2) using the management platform to create basic table student (Sno,sname,ssex,sage,sdept), Course (Cno,cname,ccpno,ccredit), SC (sno,cno,grade). The database in the management platform taskbar is selected as S_c.
A To create a new query, type the following command under the form:
CREATE TABLE Student ( Sno char (9) PRIMARY KEY,
sname char UNIQUE,
ssex char (2),
S
Job Title:1. Check all records of elective course ' 3-105 ' and score 60 to 80. Note: Used to specify a range using between and, you can also use an and connector;Answer:Law 1:select * from SC where course number = ' 3-105 ' and score between;Law 2:select * from SC where course number = ' 3-105 ' and score > score 2. Search for records with 85, 86, or 88 results. Note: Used to make a collection use the In k
Problem description:
Create three tables to manage job business training information:S (s #, Sn, SD, SA) s #, Sn, SD, and SA represent the student ID, Student name, organization, and student age respectively.C (C #, CN) C #, CN represents the course number and Course name respectively.SC (s #, C #, g) s #, C #, and G represent Student IDs, elective course numbers, and academic scores respectively.1. Use standard SQL nested statements to query the student ID and name of the elective course named
1. The last step of MySQL installation in XP prompts the service cocould not be started. Error: 0 error.Solution:
Start-run, enter "services. msc" to check whether MySQL service existsIf yes and cannot be started manuallyOpen the registry and go to "HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services"Delete the service corresponding to MySQL
Control Panel-add and deleteProgram-Delete MySQL.
Delete C: // programe files/MySQLDelete c: \ Documents ents and Settings \ All Users \ Applic
Tags: group between day SQL greater than the values language full teacherTopicStudent (SID, Sname, Sage, ssex)--Student Information sheet (student number increment, student name, student birth date, gender);Teacher (TID, tname)--Teacher Information sheet (teacher number increment, teacher name)Course (CID, CNAME, TID)--Curriculum (course number increment, course name, teacher number foreign key)SC (SID, CID, score)--score table (student number, course
Author: GW------------------------Data Query------------------------------select [all|distinct]--from --where --[group by --[group by Distinct does not show duplicate resultsASC AscendingDesc Descending--Check all student's number and name--select Sno,sname from Student--select sno,sname,sdept from Student--select * FROM Student--The following as Brithday is a name for the computed column--select Sname,2014-sage as brithday from student--select sname, ' Year of birth: ', 2014-sage,upper (sdept)
) Teacher tableProblem:1, the inquiry "001" course is higher than "002" of all students of the school number;Select a.s#From (select S#,score from SC where c#= ' 001′) A,(select S#,score from SC where c#= ' 002′) bwhere A.score>b.score and a.s#=b.s#;2, the query average score is more than 60 points of the student's number and average score;Select S#,avg (Score)From SCGROUP BY s# have AVG (score) >60;3, inqu
Label:Student (s#,sname,sage,ssex) Student tableCourse (c#,cname,t#) timetableSC (s#,c#,score) score tableTeacher (t#,tname) Teacher table Problem:1, the inquiry "001" course is higher than "002" of all students of the school number;Select a.s#From (select S#,score from SC where c#= ' 001′) A,(select S#,score from SC where c#= ' 002′) bwhere A.score>b.score and a.s#=b.s#; 2, the query average score is more
the use of the above keyword method. Student (s#,sname,sage,ssex) Student Table Course (c#,cname,t#) Timetable SC (s#,c#,score) score table teacher (t#,tname) Teacher Table questions:1, the query "001" Course than "002"study number of all students with high course performance; Select A.s#from (select S#,score from SC where C #= ' 001A, (select S#,score from SC w
Ixgbe drive.
$ wget http://sourceforge.net/projects/e1000/files/ixgbe%20stable/3.23.2/ixgbe-3.23.2.tar.gz
Compile Ixgbe driver as follows.
$ tar xvfvz ixgbe-3.23.2.tar.gz
$ cd ixgbe-3.23.2/src
$ make
Step three: Check the Ixgbe drive
After compiling, you will see the creation of the Ixgbe.ko in the IXGBE-3.23.2/SRC directory. This is the Ixgbe drive that will be loaded into the kernel.
Check the kernel module information with the Modinfo command. Note tha
SceneI use the database is mysql5.6, the following simple introduction of the next scenarioCurriculumCREATE TABLE Course (c_id int PRIMARY key,name varchar (10))Data 100 articleStudent table:CREATE TABLE Student (ID int PRIMARY key,name varchar (10))Data 70,000 articleStudent Score Table SCCREATE table SC ( sc_id int PRIMARY KEY, s_id int, c_id int, score int)Data 70w BarPurpose of Enquiry:Find candidates with 100 points in Chinese testQue
Query a specified column[Example 1] query the student ID and name of all students.SELECT Sno, SnameFROM Student;[Example 2] query the name, student ID, and Department of all students.SELECT Sname, Sno, SdeptFROM Student;[Example 3] query detailed records of all students.SELECT Sno, Sname, Ssex, Sage, SdeptFROM Student;OrSELECT *FROM Student;[Example 4] check the name and year of birth of all students.SELECT Sname, 2004-Sage/* assume that the year of the current year is 2004 */FROM Student;[Examp
Student (s#,sname,sage,ssex) Student tableCourse (c#,cname,t#) timetableSC (s#,c#,score) score tableTeacher (t#,tname) Teacher tableProblem:1, the inquiry "001" course is higher than "002" of all students of the school number;Select A.s#from (select S#,score from SC where c#= ' 001′) A, (select S#,score from SC where c#= ' 002′) bwhere A.score>b.sc Ore and A.s#=b.s#;s2, the query average score is more than
--about the primary foreign key exercises--adding and removing primary and foreign key syntax--deleting FOREIGN KEY syntax: ALTER TABLE name DROP constraint foreign KEY constraint name--Add foreign KEY syntax: ALTER TABLE NAME-constraint foreign KEY constraint name Forei GN key (column name) references Reference foreign key table (column name)--Delete primary KEY syntax: ALTER TABLE name DROP constraint PRIMARY KEY constraint name--Add PRIMARY KEY syntax: ALTER TABLE name ADD constraint PRIMARY
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This output shows that the local machine is directing traffic to addresses such as 202.0.190.89 and 202.0.38.31. This operation may involve traffic, program downloading, or leeching.
Maliciously guess, will this programmer also like to use the root account to connect to the database? First, find the location of the website root document and execute grep DocumentRoothttpd. conf. The obtained path is/opt/lampp/htdocs. Go to this directory and find the config file. php, open it, my god
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