udemy sql course

The only reason for backupThe only reason for the backup is that we can restore when I first became a SQL Server database administrator, as long as the backup work can run successfully, I feel that everything is fine. I'll look at the SQL Server Agent to make sure those jobs are running, and that's it.I think as long as the disaster occurred, I just need to do a recovery. How hard can this be? Theoretically

13 Tuesday course 2018.01.15 mysql user management, common SQL statements, mysql database backup and recovery, 13.4 mysql user management By default, mysql has a root user, but the root directory permission is too high, which is dangerous. Therefore, you need to create a new user and grant it the corresponding permissions. User Creation Method Grant indicates authorization. all indicates all permissions.

Label:Today, I mainly review the previous sub-query, and then learn the connection query join on the content.Such as:　　Select Renyuan.code,name,age, Sex, Bumen.bname,bceo from Renyuan,bumen where Renyuan.bc=bumen.bcodeWrite the above query statement as a connection query:Select Renyuan.code,name,age, Sex, Bumen.bname,bceo from Renyuan joins Bumen on Renyuan.bc=bumen.bcodeAfter that, I learned about local variables.Cases:DECLARE @code intSet @code =10003Select age from Renyuan where [email protec

to a consistent state at the time of the most recent dump.2. Load the corresponding log file copy to redo the completed transaction* Checkpoint (Checkpoint)* When the system is restored, the entire log file needs to be searched to determine whether the transaction was aborted or completed.1. The search process is too time consuming2. Most transactions that need to be re-made have their updates written to the database. Although they do not have adverse consequences for their re-But it will make

Label:Build table: 1 Create TableScore (2Namevarchar( -), 3Coursevarchar( -), 4Scoreint) 5 6 Go 7 8 Insertscore9 Select 'Hanmeimei','Chinese',Bayi Union All Ten Select 'Hanmeimei','Mathematics', the Union All One Select 'Hanmeimei',' History',Bayi Union All A Select 'Hanmeimei','Geography', the Union All - Select 'Lilei','Chinese', the Union All - Select 'Lilei','Mathematics', - Union All the Select 'Jimgreen','Chinese',Bayi Union All - Select 'Jimgreen','Mathematics', -

I. A database comprising four tables: Student table (Student), course Schedule (Course), score table (score) and teacher Information sheet (Teacher). The structure of the four tables, as shown in table 1-1 (i) to table (iv), is shown in table 1-2 table (i) ~ table (iv). Create four tables with SQL statements and complete related topics.Table 1-1 table Structure o

,state)User gas Consumption chart: Gas_consume (uno,time,gid,num,state)Employee Information Sheet: Employee (WNO,PASSWD)Permission table: Rights (Rightid,comment,function)Employee Permissions Table: Staffrignt (Wno,rightid)Analysis: Initial status information is automatically generated in the energy consumption record when the user registers The Permissions table design contains: Permission number, description and function, when adding permissions, only need to add a row, employees

Department table), the insert succeeds: 7, non-null constraintsA non-null constraint (NOT NULL), which can be understood by a name, is a non-null constrained column that must not be empty when inserting a value. Violations of non-null constraints in MySQL, will not error, there will only be warnings, such as the following statement: INSERT INTO employee(id,name,salary,phone,in_dpt) VALUES(03,‘Jim‘,3400,119119,‘dpt2‘); #INSERT成功 age为空，因为没有非空约束，表中显示NULL INSERT INTO employee(id,name,age,phone,in_

, data has become an important resource and the development of new "energy", database technology has been applied to all walks of life and various aspects of the actual business data management. In the modern information society, all the business and application systems related to data information need the support of database technology. This course is a major public foundation course for computer majors, e

new empty database testusing the command: mysql -u root #因为在上一步已经退出了MySQL，现在需要重新登录 CREATE DATABASE test; #新建一个名为test的数据库 Again Ctrl + Z exit MySQL, then enter the statement to restore, the bak.sql just backed up to the test database: test We enter a command to view the table of the Tset database to verify the success of the recovery: mysql -u root #因为在上一步已经退出了MySQL，现在需要重新登录 use test #连接数据库test SHOW TABLES; #查看test数据库的表 You can see 4 tables and a

the table (1) Modify a value in the tableMost of the time we need to make changes not the entire database or the entire table, but one or more of the data in the table, which requires us to use this command to achieve precise modification:UPDATE 表名字 SET 列1=值1,列2=值2 WHERE 条件;For example, we want to change Tom's age to 21,salary to 3000: Note: Be sure to have a where condition, or there will be consequences you don't want to see (2) Delete a row of recordsDeleting a row of data in a