From 7caad80fb4d80d55ac0f25c8e2643f7307253f2d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=88=B4=E4=BF=8A=E9=94=8B?= <379646933@qq.com>
Date: Wed, 21 Sep 2022 10:38:29 +0000
Subject: [PATCH 1/2] =?UTF-8?q?2022.9.21=E4=BD=9C=E4=B8=9A?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 戴俊锋 <379646933@qq.com>
---
 .../2022.9.21\344\275\234\344\270\232.sql"    | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 "\346\210\264\344\277\212\351\224\213/\344\275\234\344\270\232/2022.9.21\344\275\234\344\270\232.sql"

diff --git "a/\346\210\264\344\277\212\351\224\213/\344\275\234\344\270\232/2022.9.21\344\275\234\344\270\232.sql" "b/\346\210\264\344\277\212\351\224\213/\344\275\234\344\270\232/2022.9.21\344\275\234\344\270\232.sql"
new file mode 100644
index 0000000..15c6d95
--- /dev/null
+++ "b/\346\210\264\344\277\212\351\224\213/\344\275\234\344\270\232/2022.9.21\344\275\234\344\270\232.sql"
@@ -0,0 +1,71 @@
+--13. ��ƽ���ɼ��Ӹߵ�����ʾ����ѧ�������пγ̵ijɼ��Լ�ƽ���ɼ�
+select sc.SId,c.Cname,score,t.ƽ���� from sc
+inner join Course c on c.cid = sc.CId
+inner join
+(
+select sid,avg(score)ƽ���� from sc
+group by sid 
+) t
+on t.SId = sc.sid 
+
+order by t.ƽ���� desc
+--14. ��ѯ���Ƴɼ���߷֡���ͷֺ�ƽ���֣�
+--��������ʽ��ʾ���γ� ID���γ� name����߷֣���ͷ֣�ƽ���֣������ʣ��е��ʣ������ʣ�������
+--����Ϊ>=60���е�Ϊ��70-80������Ϊ��80-90������Ϊ��>=90
+--Ҫ������γ̺ź�ѡ����������ѯ����������������У���������ͬ�����γ̺���������
+select sc.CId,c.Cname,
+(select max(score) from sc sc1 where sc.CId = sc1.CId)��߷�,
+(select min(score) from sc sc1 where sc.CId = sc1.CId)��ͷ�,
+convert(decimal(5,2),(select avg(score) from sc sc1 where sc.cid = sc1.cid))ƽ����,
+concat(convert(decimal(5,2),(select (count(*)*100)/1.0/(select count(*) from sc sc3 where sc3.cid = sc.cid ) from sc sc2 where sc.cid = sc2.cid and sc2.score >= 60)),'%') ������,
+concat(convert(decimal(5,2),(select (count(*)*100)/1.0/(select count(*) from sc sc3 where sc3.cid = sc.cid ) from sc sc2 where sc.cid = sc2.cid and sc2.score  between 70 and 80)),'%') ���,
+concat(convert(decimal(5,2),(select (count(*)*100)/1.0/(select count(*) from sc sc3 where sc3.cid = sc.cid ) from sc sc2 where sc.cid = sc2.cid and sc2.score between 80 and 90)),'%') ������,
+concat(convert(decimal(5,2),(select (count(*)*100)/1.0/(select count(*) from sc sc3 where sc3.cid = sc.cid ) from sc sc2 where sc.cid = sc2.cid and sc2.score >= 90)),'%') ������
+from sc
+inner join Course c 
+on c.CId = sc.CId
+group by sc.CId,c.Cname
+
+
+--15. �����Ƴɼ��������򣬲���ʾ������ Score �ظ�ʱ�������ο�ȱ
+select s.sid,sname,t1.��������,t2.��ѧ����,t3.Ӣ������ from student s
+left join
+(
+select sid,rank() over(order by score desc) �������� from sc where cid = '01'
+) t1 on t1.sid = s.sid 
+inner join
+(
+select sid,rank() over(order by score desc) ��ѧ���� from sc where cid = '02'
+) t2 on t2.sid = s.sid
+left join 
+(
+select sid,rank() over(order by score desc) Ӣ������ from sc where cid = '03'
+) t3 on t3.sid = s.sid
+--15.1 �����Ƴɼ��������򣬲���ʾ������ Score �ظ�ʱ�ϲ�����
+select s.sid,sname,t1.��������,t2.��ѧ����,t3.Ӣ������ from student s
+left join
+(
+select sid,dense_rank() over(order by score desc) �������� from sc where cid = '01'
+) t1 on t1.sid = s.sid 
+inner join
+(
+select sid,dense_rank() over(order by score desc) ��ѧ���� from sc where cid = '02'
+) t2 on t2.sid = s.sid
+left join 
+(
+select sid,dense_rank() over(order by score desc) Ӣ������ from sc where cid = '03'
+) t3 on t3.sid = s.sid
+--16. ��ѯѧ�����ܳɼ����������������ܷ��ظ�ʱ�������ο�ȱ
+select t.SId,t.�ܷ�,dense_rank() over (order by �ܷ� desc) ����
+from
+(
+select sid,sum(score) �ܷ� from sc
+group by sid 
+) t
+--16.1 ��ѯѧ�����ܳɼ����������������ܷ��ظ�ʱ���������ο�ȱ
+select t.SId,t.�ܷ�,rank() over (order by �ܷ� desc) ����
+from
+(
+select sid,sum(score) �ܷ� from sc
+group by sid 
+) t
\ No newline at end of file
-- 
Gitee


From 589cb2541dc3df7c20f149184b03740cb9aa98a3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=88=B4=E4=BF=8A=E9=94=8B?= <379646933@qq.com>
Date: Wed, 21 Sep 2022 10:39:09 +0000
Subject: [PATCH 2/2] =?UTF-8?q?2022.9.21=E7=AC=94=E8=AE=B0--=E5=85=B3?=
 =?UTF-8?q?=E8=81=94=E5=AD=90=E6=9F=A5=E8=AF=A2?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 戴俊锋 <379646933@qq.com>
---
 ...\201\224 \345\255\220\346\237\245\350\257\242.md" | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 "\346\210\264\344\277\212\351\224\213/\347\254\224\350\256\260/2022.9.21--\345\205\263\350\201\224 \345\255\220\346\237\245\350\257\242.md"

diff --git "a/\346\210\264\344\277\212\351\224\213/\347\254\224\350\256\260/2022.9.21--\345\205\263\350\201\224 \345\255\220\346\237\245\350\257\242.md" "b/\346\210\264\344\277\212\351\224\213/\347\254\224\350\256\260/2022.9.21--\345\205\263\350\201\224 \345\255\220\346\237\245\350\257\242.md"
new file mode 100644
index 0000000..c7d1442
--- /dev/null
+++ "b/\346\210\264\344\277\212\351\224\213/\347\254\224\350\256\260/2022.9.21--\345\205\263\350\201\224 \345\255\220\346\237\245\350\257\242.md"	
@@ -0,0 +1,12 @@
+# 1.关联子查询
+
+**（1）先从主查询的表中的列取出第一个值，进入子查询中，得到子查询结果，然后返回父查询，判断父查询的where子句条件，则返回整个语句的第1条结果。**
+
+**（2）重复上述操作，直到所有主查询中的表中的列记录取完为止。得出整个语句的结果集，就是最后的答案。**
+
+```sql
+--关联子查询：内部查询需要引用外部表已查询出的信息
+select birth,name 姓名,gender 性别 from tb_student t1
+where birth = (select min(birth) from tb_student t2 where t2.gender=t1.gender)
+```
+
-- 
Gitee