更新命令是一种数据操作命令,用于编辑表的记录。它可用于基于条件更新单个行,基于用户给出的条件更新所有行或一组行。
它与 SET 子句一起使用,在操作上,WHERE 子句可用于匹配条件 -
例 1
下面给出了一个使用 update 命令的示例 -
update table student set name=’sneha’ where branch=’CSE’;
例 2
下面给出的是使用更新命令的另一个示例 -
create table employee(ename varchar(30),department varchar(20));
insert into employee values('pinky','CSE');
insert into employee values('priya','ECE');
insert into employee values('hari','EEE');
select * from employee;
update employee set ename='sneha' where department='CSE';
select * from employee;
输出
您将获得以下输出 -
pinky|CSE
priya|ECE
hari|EEE
sneha|CSE
priya|ECE
hari|EEE
更新列的值
下面给出的是更新表员工设置年龄=年龄+1的示例:
create table employee(ename varchar(30),department varchar(20), age number(30));
insert into employee values('ram','projectmanager',40);
insert into employee values('priya','assistant director',45);
insert into employee values('hari','developer',46);
select * from employee;
update employee set age=age+2;
select * from employee;
输出
您将获得以下输出 -
ram|projectmanager|40
priya|assistant director|45
hari|developer|46
ram|projectmanager|42
priya|assistant director|47
hari|developer|48
在一个语句中更新多个列
下面给出的是更新表格工资集的示例 -
这里
- 奖金=奖金+5000
- 基本=基本+(0.2*奖金)
例
create table employee(ename varchar(30),department varchar(20), age number(30), salary number(20));
insert into employee values('ram','projectmanager',40,50000);
insert into employee values('priya','assistant director',45,45000);
insert into employee values('hari','developer',46,30000);
select * from employee;
update employee set age=age+2,
salary= salary+5000;
select * from employee;
输出
您将获得以下输出 -
ram |projectmanager |40|50000
priya|assistant director|45|45000
hari |developer |46|30000
ram |projectmanager |42|55000
priya|assistant director|47|50000
hari |developer |48|35000