基础
# 每一列都要指定对应的类型
# 字符串:varchar(N)
# 整数:int
# 小数:double
# 年月日:date
# 年月日时分秒:datetime
# 创建表
create table if not exists db_bigdata.student(
stuid varchar(10),
stuname varchar(10),
age int,
sex varchar(2),
email VARCHAR(100)
);
# 列举表
use db_bigdata;
show tables ;
# 描述表
desc db_bigdata.student;
# 删除表
drop table if exists db_bigdata.student;
# 修改列的数据类型
ALTER TABLE db_bigdata.student modify stuname VARCHAR(50);
# 修改列的字符集
ALTER TABLE db_bigdata.student MODIFY stuname VARCHAR(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
# 修改列的约束
ALTER TABLE db_bigdata.student MODIFY age INT NOT NULL;
# 综合示例
ALTER TABLE db_bigdata.student
MODIFY stuname VARCHAR(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci,
MODIFY age INT NOT NULL,
MODIFY email VARCHAR(100) UNIQUE NOT NULL;
进阶
# 进阶
CREATE TABLE if not exists db_bigdata.student (
student_id INT AUTO_INCREMENT PRIMARY KEY,