sql crash course

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

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