我创建了一个名为Youtuber的表,代码如下:
create table Channel (
codChannel int primary key,
name varchar(50) not null,
age float not null,
subscribers int not null,
views int not null
)
在此表中,有2个频道:
|codChannel | name | age | subscribers | views |
| 1 | PewDiePie | 28 | 58506205 | 16654168214 |
| 2 | Grandtour Games | 15 | 429 | 29463 |
所以,我想将Grandtour Games的年龄编辑为" 18"。我怎么能用update
做到这一点?
我的代码是对的吗?
update age from Grandtour Games where age='18'
答案 0 :(得分:3)
不,在update
中,您必须遵循以下顺序:
update tableName set columnWanted = 'newValue' where columnName = 'elementName'
在你的代码中,输入:
update Channel set age=18 where name='Grandtour Games'
以下评论:
/* Channel is the name of the table you'll update
set is to assign a new value to the age, in your case
where name='Grandtour Games' is referencing that the name of the Channel you want to update, is Grandtour Games */
答案 1 :(得分:0)
alter table
更改架构(添加,更新或删除列或键,这类事情)。
更新表会更改表中的数据而不更改架构。
所以这两者真的很不一样。
答案 2 :(得分:0)
这是你的回答 -
-> ALTER is a DDL (Data Definition Language) statement
UPDATE is a DML (Data Manipulation Language) statement.
->ALTER is used to update the structure of the table (add/remove field/index etc).
Whereas UPDATE is used to update data.
希望这有帮助!