SQL——基礎語法
阿新 • • 發佈:2020-12-31
技術標籤:linux學習筆記
1.基本資料型別
2.建立表
creat table tablename (column_name column_type);
例項:
CREATE TABLE IF NOT EXISTS `runoob_tbl`(
`runoob_id` INT UNSIGNED AUTO_INCREMENT,
`runoob_title` VARCHAR(100) NOT NULL,
`runoob_author` VARCHAR(40) NOT NULL,
`submission_date` DATE,
PRIMARY KEY ( `runoob_id` )
)ENGINE=InnoDB DEFAULT CHARSET=utf8;
解析:
- runoob_tbl:表名
- runoob_id:表頭
- INT UNSIGNED:runoob_id的資料型別為無符號整型
- AUTO_INCREMENT:自增屬性,runoob_id會逐行加1
- NOT NULL:設定runoob_title的值不能為空,操作資料庫時如果輸入該欄位的資料為NULL ,就會報錯
- PRIMARY KEY:設定runoob_tbl表的主鍵為runoob_id
- ENGINE:設定儲存引擎
- CHARSET:設定編碼
3.刪除表
drop table tablename;
例項:
drop table runoob_tbl;
4.增刪改查
1. 插入資料
insert into table_name ( field1, field2,...fieldN )
values(value1, value2,...valueN );
例項:
insert into runoob_tbl (runoob_title, runoob_author, submission_date)
values("學習 PHP", "菜鳥教程", NOW());
2. 查詢資料
select column_name, column_name
from table_name [where Clause][limit N][ offset M]
例項1:顯示整張表
select * from runoob_tbl;
3. 刪除資料
delete from table_name [where Clause]
例項:
delete from runoob_tbl where runoob_id=3;
4. 修改資料
update table_name set field1=new-value1, field2=new-value2···
[where Clause]
例項:
update runoob_tbl set runoob_title='學習 C++' where runoob_id=3;