Data Operations in data manipulation language

-- Table data operations

-- Input data

Select * from student

-- Note: into used between insert and table names is an optional keyword.

Insert into student (student ID, name, gender, age, Major)

Values ('003 ', 'yanglil', 'female', 18, 'Family Planning ')

Insert into student (student ID, name, gender, age, Major)

Values ('004 ', 'yanglil', 'female', 18, 'Family Planning ')

Delete student where student ID = '004'

Alter table student

Add constraint ck check (Gender in ('male', 'female '))

Insert into student

(Student ID, name, gender, age, Major)

Values ('005 ', 'zhang san', 'mal', 18, 'network Project ')

-- Modify Table Data

-- In data manipulation language, modifying data means updating data with the update keyword.

/*

Syntax:

Update table name

Set column name = new data

Where condition expression

*/

Use test

Go

Alter table student

Add remarks char (20)

Update student

Set gender = 'graduated'

-- Based on conditions and new data

Update student

Set remarks = 'Students on reading'

Where name = 'wang fang'

-- Delete data

-- Delete a row of records each time

/*

Syntax structure

Deleted table name

Where condition expression

*/

Delete student

Where student ID = '005'

-- Delete all records of a table at one time: Clear the table

-- There are two methods

-- Method 2 is faster

-- Method 1;

Delete Course Selection

-- Method 2:

Truncate table Course Selection

//

-- Delete a table

Drop table hh

//