七、sql基础：1.DML语句--【Oracle数据库】

七、DML语句

Data Manipulation Language，数据操纵语言，增删改。

1. INSERT语句

1.1 格式一

insert into student (stu_id, stu_name) values(12, ‘zhao’);

1.2 格式二

insert into student values (13, ‘xudong’ , null, null);

1.3 格式三：从另一个表中Copy一行

insert into sales_reps (id, name, salary, commission_pot)
        select employee_id, last_name, salary, commission_pot
        from  employees
        where   job_id  like  '%REP%';

1.4 格式四：使用子查询作为插入目标

    insert  into  
        (select  stu_id, stu_name, job_id  from employees where stu_id = 100)
    values (100, 'zhao', 12);

可以加上with check option来校验

    insert  into  
        (select  stu_id, stu_name, job_id  from employees where stu_id = 100 with check option)
    values (101, 'zhao', 12);

这样插入的时候就会报错，因为前面id=100，插入的是101

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2. UPDATE语句

2.1格式一：更新某些符合条件的行中的某些列为具体值

    update  student  set  stu_name = 'zhao', stu_sex = 2
        where stu_id = 1 ;

2.2格式二：使用子查询的结果作为更新后的值

update  student  
    set  class_name = (select class_name from class where class_id = 11)
      class_num = (select class_num from class where class_id = 11)
    where  stu_id = 11;

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3. DELETE语句

3.1格式一：删除某些符合条件的记录

delect  from  student 
    where stu_id = 10;

3.2格式二：删除一张表中所有的记录

delect from student;
truncate table student;语句也可以对表进行清空，效率更快，但是不能回滚。

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4. MERGE语句:比较、整合