From 1677380a072ff3976d5213a4ccfded1775fd3263 Mon Sep 17 00:00:00 2001
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 <11785161+zhao-xianglin@user.noreply.gitee.com>
Date: Fri, 8 Sep 2023 01:53:03 +0000
Subject: [PATCH] =?UTF-8?q?=E6=95=B0=E6=8D=AE=E5=8F=AF?=
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Signed-off-by: 赵向林 <11785161+zhao-xianglin@user.noreply.gitee.com>
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+
+
+数据库设计三大范式.
+1.第一范式:每个属性,也就是字段要求不可再分割、也就要求有原子性.
+2.第二范式:在满足第一范式的基础上要求非主键字段完全依赖主键. （有联合主键时，非主键要同时完全依赖两个主键而不能部分依赖）
+3.第三范式:在满足第二范式的基础上,要求非主键字段要直接依赖于主键.
+
+今天复习了老师教的内容，准备一下大考补考
+
+```sql
+create database school charset utf8;
+use school;
+create table student(
+    id int,
+    name varchar(11)
+    );
+insert into student values (1,'张三');
+insert into student values (2,'李四');
+insert into student values (3,'王五');
+insert into student values (4,'赵六');
+
+create table laoshi(
+    id int,
+    name varchar(11)
+);
+insert into laoshi values (1,'赵老师');
+insert into laoshi values (1,'望老师');
+insert into laoshi values (1,'黎老师');
+insert into laoshi values (1,'无老师');
+drop table laoshi;
+create table calss(
+    id int,
+    name varchar(11)
+);
+insert into calss values (1,'1班');
+insert into calss values (2,'2班');
+insert into calss values (3,'三班');
+insert into calss values (4,'五班');
+```
+
-- 
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