From 5a494bb20baf3abc41378a3ee905992220b304c0 Mon Sep 17 00:00:00 2001
From: syneffort <syneffort@gmail.com>
Date: Thu, 22 Sep 2022 10:50:22 +0900
Subject: [PATCH] join

---
 join (ansi).sql      | 12 ++++++++++++
 join (cartesian).sql | 31 +++++++++++++++++++++++++++++++
 simple join.sql      | 13 +++++++++++++
 3 files changed, 56 insertions(+)
 create mode 100644 join (ansi).sql
 create mode 100644 join (cartesian).sql
 create mode 100644 simple join.sql

diff --git a/join (ansi).sql b/join (ansi).sql
new file mode 100644
index 0000000..3063f6a
--- /dev/null
+++ b/join (ansi).sql	
@@ -0,0 +1,12 @@
+USE Study
+GO
+
+-- INNER JOIN
+SELECT ENAME, DNAME
+FROM EMPLOYEE
+	INNER JOIN DEPARTMENT ON EMPLOYEE.DNO = DEPARTMENT.DNO
+
+-- OUTER JOIN
+SELECT E.ENAME AS EMPLOYEE, M.ENAME AS MANAGER
+FROM EMPLOYEE AS E
+	LEFT OUTER JOIN EMPLOYEE AS M ON E.MANAGER = M.ENO
\ No newline at end of file
diff --git a/join (cartesian).sql b/join (cartesian).sql
new file mode 100644
index 0000000..1680e1a
--- /dev/null
+++ b/join (cartesian).sql	
@@ -0,0 +1,31 @@
+USE Study
+GO
+
+SELECT * FROM EMPLOYEE
+SELECT * FROM DEPARTMENT
+
+-- Cartesian product: ¸ðµç Æ©ÇÃ½Ö »ý¼º (same as Cross join)
+SELECT * FROM EMPLOYEE, DEPARTMENT
+
+select * from EMPLOYEE
+select * from SALGRADE
+
+-- Theta join
+SELECT ENAME, GRADE
+FROM EMPLOYEE, SALGRADE
+WHERE LOWSAL <= SALARY AND SALARY <= HIGHSAL
+
+SELECT ENAME, GRADE
+FROM EMPLOYEE, SALGRADE
+WHERE SALARY BETWEEN LOWSAL AND HIGHSAL
+
+-- Self join
+SELECT E.ENAME AS ENAME, M.ENAME AS MANAGER
+FROM EMPLOYEE AS E, EMPLOYEE AS M
+WHERE E.MANAGER = M.ENO
+
+-- Mulitple join
+SELECT ENAME, GRADE, DNAME
+FROM EMPLOYEE, SALGRADE, DEPARTMENT
+WHERE SALARY BETWEEN LOWSAL AND HIGHSAL
+	AND EMPLOYEE.DNO = DEPARTMENT.DNO
\ No newline at end of file
diff --git a/simple join.sql b/simple join.sql
new file mode 100644
index 0000000..297cf9c
--- /dev/null
+++ b/simple join.sql	
@@ -0,0 +1,13 @@
+USE Study
+GO
+
+SELECT * FROM EMPLOYEE
+SELECT * FROM DEPARTMENT
+
+SELECT *
+FROM EMPLOYEE, DEPARTMENT
+WHERE ENO = 103 AND EMPLOYEE.DNO = DEPARTMENT.DNO
+
+SELECT *
+FROM EMPLOYEE AS E, DEPARTMENT AS D
+WHERE ENO = 103 AND E.DNO = D.DNO
\ No newline at end of file