From c59f43c01265d0516b9138c3b41f7a2924c74308 Mon Sep 17 00:00:00 2001
From: syneffort <syneffort@gmail.com>
Date: Mon, 26 Sep 2022 11:25:28 +0900
Subject: [PATCH] ranking

---
 first_value, lag, lead.sql    | 16 ++++++++++++++++
 group rank (partition by).sql | 17 +++++++++++++++++
 top rank.sql                  | 22 ++++++++++++++++++++++
 3 files changed, 55 insertions(+)
 create mode 100644 first_value, lag, lead.sql
 create mode 100644 group rank (partition by).sql
 create mode 100644 top rank.sql

diff --git a/first_value, lag, lead.sql b/first_value, lag, lead.sql
new file mode 100644
index 0000000..22f34b2
--- /dev/null
+++ b/first_value, lag, lead.sql	
@@ -0,0 +1,16 @@
+USE Study
+GO
+
+-- 행순서 함수
+
+-- FISRT_VALUE: 첫번째 튜플만
+SELECT DISTINCT DNO, FIRST_VALUE(SALARY) OVER (PARTITION BY DNO ORDER BY SALARY DESC) AS HIGH_SALARY
+FROM EMPLOYEE
+
+-- LAG/LEAD: 정렬 기준 선행/후행 값 출력
+SELECT 
+	DISTINCT ENAME, 
+	SALARY, 
+	LAG(SALARY, 1) OVER(ORDER BY SALARY DESC) AS LAG_SALARY,
+	LEAD(SALARY, 1) OVER(ORDER BY SALARY DESC) AS LEAD_SALARY
+FROM EMPLOYEE
\ No newline at end of file
diff --git a/group rank (partition by).sql b/group rank (partition by).sql
new file mode 100644
index 0000000..4604158
--- /dev/null
+++ b/group rank (partition by).sql	
@@ -0,0 +1,17 @@
+USE Study
+GO
+
+-- 그룹별 순위 지정
+SELECT ENAME, SALARY, DNO, RANK() OVER (PARTITION BY DNO ORDER BY SALARY DESC) AS RANK_DEPT
+FROM EMPLOYEE
+
+-- 각 그룹 급여기준 2위인 사원의 부서정보, 이름, 급여, 순위 조회
+SELECT *
+FROM 
+	(SELECT DNO, ENAME, SALARY, RANK() OVER (PARTITION BY DNO ORDER BY SALARY DESC) AS RANK_VALUE
+	FROM EMPLOYEE) AS TEMP
+WHERE RANK_VALUE = 2
+
+-- 그룹별 집단 함수 사용
+SELECT DISTINCT DNO, AVG(SALARY) OVER (PARTITION BY DNO) FROM EMPLOYEE
+SELECT DISTINCT DNO, AVG(SALARY) FROM EMPLOYEE GROUP BY DNO
\ No newline at end of file
diff --git a/top rank.sql b/top rank.sql
new file mode 100644
index 0000000..63c204b
--- /dev/null
+++ b/top rank.sql	
@@ -0,0 +1,22 @@
+USE Study
+GO
+
+-- TOP
+
+SELECT TOP(5) * FROM EMPLOYEE ORDER BY SALARY DESC
+
+SELECT TOP(5) WITH TIES * FROM EMPLOYEE ORDER BY SALARY DESC
+
+SELECT TOP(20) PERCENT * FROM EMPLOYEE ORDER BY SALARY DESC
+
+SELECT TOP(5) * FROM EMPLOYEE ORDER BY SALARY DESC
+
+
+-- RANK
+SELECT ENAME, SALARY, RANK() OVER (ORDER BY SALARY DESC) AS SALRANK FROM EMPLOYEE
+
+SELECT ENAME, SALARY, DENSE_RANK() OVER (ORDER BY SALARY DESC) AS SALDENSERANK FROM EMPLOYEE
+
+SELECT ENAME, SALARY, ROW_NUMBER() OVER (ORDER BY SALARY DESC) AS SALROWRANK FROM EMPLOYEE
+
+SELECT ENAME, SALARY, NTILE(5) OVER (ORDER BY SALARY DESC) AS RANKNTILE FROM EMPLOYEE