MYSQL 数据库的创建数据库，删除，修改，增添表数据的简单操作

一时失言乱红尘 2022-05-27 01:22 216阅读 0赞

CREATE DATABASE xia12;/\*创建数据库\*/  /\*运行时注意一下可能会出现xia1数据库exists；，那就把本句注释掉\*/  
DROP DATABASE xia12;/\*删除数据库\*/  
CREATE DATABASE xia12;  
USE  xia12;/\*使用xia1数据库\*/  
/\*SHOW DATABASES;/\*显示本机数据库\*/  
  
  
CREATE TABLE IF NOT EXISTS wen\_tbl(stu\_id CHAR(12)  NOT NULL PRIMARY KEY,  
stu\_name VARCHAR(13) UNIQUE NOT NULL,  
age TINYINT UNSIGNED ,  
sex CHAR(2) DEFAULT '男' CHECK(sex='男' OR sex='女'),  
major CHAR(10),grade FLOAT(5,2)  
)ENGINE=InnoDB;/\*创建表\*/  
/\*SHOW TABLES;/\*显示表\*/  
/\*ALTER DATABASE xia1   
MODIFY FILE  
（NAME=wen\_tbl,SIZE= 10,MAXSIZE=100,FILEGROWTH=5);\*/  
/\*DROP table table\_name;/\*删除表\*/  
ALTER TABLE wen\_tbl ADD birthday datetime;/\*增加属性birthday\*/  
  
  
ALTER TABLE wen\_tbl DROP birthday;/\*删除属性\*/  
INSERT INTO wen\_tbl(stu\_id,stu\_name,age,sex,major,grade)   
VALUES( 16111545234,"小雨",11,"男","C++",89.90);/\*增添数据\*/  
INSERT INTO wen\_tbl(stu\_id,stu\_name,age,sex,major,grade)   
VALUES( 16111545235,"小红",11,"女","php",79.90);  
INSERT INTO wen\_tbl(stu\_id,stu\_name,age,sex,major,grade)   
VALUES( 16111545236,"小军",11,"男","C",89.90);  
INSERT INTO wen\_tbl(stu\_id,stu\_name,age,sex,major,grade)   
VALUES( 16111545238,"小兰",11,"女","sql",89.90);  
DELETE FROM wen\_tbl WHERE stu\_id="16111545238";/\*删除小兰数据信息\*/  
UPDATE wen\_tbl SET major="JAVA" WHERE stu\_id="16111545236";/\*修改数据当学号为238的C被修改成java\*/  
SELECT \* from wen\_tbl WHERE stu\_name="小雨";/\*查询数据\*/  
ALTER TABLE wen\_tbl change age 年龄 TINYINT;/\*修改列名\*/  
select \*FROM wen\_tbl;