sql基本操做之增刪改查

1. 顯示數據庫 show databases;

show databases;

2. 顯示當前數據庫

select current_database();

3. 建立數據庫

create database db_name;

4. 選擇某個數據庫

use db_name;

5. 顯示當前數據庫下的表

show tables;

6. 建立表 create table

create table if not exists my_test(
   id INT UNSIGNED AUTO_INCREMENT,
   name_people VARCHAR(40) NOT NULL,
     submission_time DATETIME,
   PRIMARY KEY(id)
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

7. 描述表結構DESC或者DESCRIBE、show columns from

DESC my_test;
SHOW COLUMNS FROM my_test; #顯示錶結構

8. 插入數據 insert into

INSERT my_test(
    id,
    name_people,
    submission_time
)
VALUES
    (1, 'Mary', NOW());

9 .查詢 select

select * from my_test;
select name_people from my_test;
select name_peole from my_test where id=1;

 

 

10. 刪除一條記錄 delete

delete from my_test where id=1;

11. 刪除表中的全部記錄，可是保存原來的表結構

delete from my_test;

12. 更新表的某一列 update

UPDATE my_test SET name_people = '陛下' WHERE id=1

13. 更新多列數據，用 ',' 逗號隔開

UPDATE my_test SET name_people = '將軍', submission_time = NOW() WHERE id=1

 14. 增長新列 alter，而後update

ALTER table my_test add name_adress VARCHAR(50) not null;
update my_test set name_adress='北京';

 15. 複製另外一張表的數據和表結構，來新建表 create，使用as關鍵詞

CREATE TABLE my_test_copy AS SELECT * FROM  my_test;
SELECT * from my_test_copy;

 

#歡迎交流