七、sql基礎：1.DML語句--【Oracle數據庫】

七、DML語句

Data Manipulation Language，數據操縱語言，增刪改。

1. INSERT語句

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：從另一個表中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：使用子查詢作爲插入目標

    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來校驗

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

這樣插入的時候就會報錯，因爲前面id=100，插入的是101

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2. UPDATE語句

2.1格式一：更新某些符合條件的行中的某些列爲具體值

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

2.2格式二：使用子查詢的結果作爲更新後的值

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語句

3.1格式一：刪除某些符合條件的記錄

delect  from  student 
    where stu_id = 10;

3.2格式二：刪除一張表中所有的記錄

delect from student;
truncate table student;語句也可以對錶進行清空，效率更快，但是不能回滾。

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4. MERGE語句:比較、整合