From e1f0635aa1da51d66d377e6ffc6eee0434574828 Mon Sep 17 00:00:00 2001
From: SunKyu Choi <98688494+luke0408@users.noreply.github.com>
Date: Tue, 17 Oct 2023 16:28:54 +0900
Subject: [PATCH] =?UTF-8?q?=F0=9F=93=9D=20[Docs]=20Integrity=20Constraints?=
 =?UTF-8?q?=20(#4)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Item 04 - Integrity Constraints/Note.md   | 47 +++++++++++++++++--
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/Chapter 04 - Intermediate SQL/Item 04 - Integrity Constraints/Note.md b/Chapter 04 - Intermediate SQL/Item 04 - Integrity Constraints/Note.md
index 0809c43..89c0e82 100644
--- a/Chapter 04 - Intermediate SQL/Item 04 - Integrity Constraints/Note.md	
+++ b/Chapter 04 - Intermediate SQL/Item 04 - Integrity Constraints/Note.md	
@@ -1,5 +1,46 @@
-# Example 1
+# Integrity Constraints
 
-> 작성자: 루카(최선규)
+> 작성자: 최선규
 
-## 목차
+## Not Null
+
+`NOT NULL` 제약 조건은 특정 컬럼에 `NULL` 값을 허용하지 않는다는 것을 의미한다.
+
+ex)
+
+  ```sql
+  CREATE TABLE table_name (
+      column_name1 datatype NOT NULL,
+      column_name2 datatype,
+      ...
+  );
+  ```
+
+## Unique
+
+'UNIQUE' 제약 조건은 특정 컬럼에 중복된 값을 허용하지 않는다는 것을 의미한다.
+
+ex)
+
+  ```sql
+  CREATE TABLE table_name (
+      column_name1 datatype UNIQUE,
+      column_name2 datatype,
+      ...
+  );
+  ```
+
+## Check clause
+
+`CHECK` 제약 조건은 특정 컬럼에 특정 조건을 만족하는 값만 허용한다는 것을 의미한다.
+
+ex)
+
+  ```sql
+  CREATE TABLE table_name (
+      column_name1 datatype,
+      column_name2 datatype,
+      ...
+      CHECK (column_name1 > 0)
+  );
+  ```