Based on the requirements, the following is a suggested database schema:
```sql
-- Table to store client information
CREATE TABLE clients (
  client_id INT PRIMARY KEY,
  org_name VARCHAR(255),
  contact_first_name VARCHAR(255),
  contact_last_name VARCHAR(255),
  email VARCHAR(255),
  address VARCHAR(255),
  preferred_contact_method VARCHAR(255)
);

-- Table to store pool member information
CREATE TABLE pool_members (
  member_id INT PRIMARY KEY,
  first_name VARCHAR(255),
  last_name VARCHAR(255),
  email VARCHAR(255),
  phone_number VARCHAR(255),
  work_address VARCHAR(255),
  home_address VARCHAR(255)
);

-- Table to store skill information
CREATE TABLE skills (
  skill_id INT PRIMARY KEY,
  skill_name VARCHAR(255),
  skill_type VARCHAR(255)
);

-- Table to store the relationship between pool members and skills
CREATE TABLE member_skills (
  member_id INT,
  skill_id INT,
  level_of_experience INT,
  PRIMARY KEY (member_id, skill_id),
  FOREIGN KEY (member_id) REFERENCES pool_members(member_id),
  FOREIGN KEY (skill_id) REFERENCES skills(skill_id)
);

-- Table to store project information
CREATE TABLE projects (
  project_id INT PRIMARY KEY,
  title VARCHAR(255),
  start_date DATE,
  end_date DATE,
  budget DECIMAL(10,2),
  description VARCHAR(255),
  phase VARCHAR(255)
);

-- Table to store the relationship between projects and pool members
CREATE TABLE project_pool_members (
  project_id INT,
  member_id INT,
  PRIMARY KEY (project_id, member_id),
  FOREIGN KEY (project_id) REFERENCES projects(project_id),
  FOREIGN KEY (member_id) REFERENCES pool_members(member_id)
);

-- Table to store unassigned projects
CREATE TABLE unassigned_projects (
  project_id INT PRIMARY KEY,
  title VARCHAR(255),
  start_date DATE,
  end_date DATE,
  budget DECIMAL(10,2),
  description VARCHAR(255),
  phase VARCHAR(255)
);

-- Table to store unassigned pool members
CREATE TABLE unassigned_pool_members (
  member_id INT PRIMARY KEY,
  first_name VARCHAR(255),
  last_name VARCHAR(255),
  email VARCHAR(255),
  phone_number VARCHAR(255),
  work_address VARCHAR(255),
  home_address VARCHAR(255)
);
```
Explanation of the database design decisions:

1. The database design is in the third normal form (3NF). Each table represents a single entity, and all the columns in a table are directly related to that entity.
2. The database design includes meaningful data integrity constraints. Primary keys are defined for each table to ensure that each record is unique, and foreign keys are used to enforce referential integrity between tables.
3. Appropriate foreign-key constraints have been included to ensure that the relationships between the tables are properly defined.
4. To satisfy the requirements of the project, unassigned\_projects and unassigned\_pool\_members tables have been added to store projects and pool members that have not been assigned to any project yet.
5. To satisfy requirement R1, the projects table has a one-to-many relationship with the clients table.
6. To satisfy requirement R2, the project\_pool\_members table has a many-to-many relationship with the pool\_members table. The primary key of the project\_pool\_members table consists of two foreign keys, project\_id and member\_id, to ensure that each pool member can only be assigned to one project if they meet the skill requirements.
7. To satisfy requirement R3, the member\_skills table has a many-to-many relationship with the pool\_members table. The level\_of\_experience column is included to capture the different levels of expertise of each pool member in each skill.
8. To
요구 사항에 따라 다음은 권장 데이터베이스 스키마입니다:```sql-- 클라이언트 정보를 저장할 테이블CREATE TABLE clients (  client_id INT PRIMARY KEY,  org_name VARCHAR(255),  contact_first_name VARCHAR(255),  contact_last_name VARCHAR(255),  이메일 VARCHAR(255),  주소 VARCHAR(255),  preferred_contact_method VARCHAR(255));-- 풀 멤버 정보를 저장하는 테이블CREATE TABLE pool_members (  member_id INT PRIMARY KEY,  first_name VARCHAR(255),  last_name VARCHAR(255),  email VARCHAR(255),  phone_number VARCHAR(255),  직장_주소 VARCHAR(255),  home_address VARCHAR(255));-- 스킬 정보를 저장하는 테이블CREATE TABLE skills (  skill_id INT PRIMARY KEY,  skill_name VARCHAR(255),  skill_type VARCHAR(255));-- 풀 멤버와 스킬 간의 관계를 저장하는 테이블 생성CREATE TABLE member_skills (  member_id INT,  skill_id INT,  level_of_experience INT,  PRIMARY KEY (member_id, skill_id),  FOREIGN KEY (member_id) REFERENCES pool_members(member_id),  FOREIGN KEY (skill_id) REFERENCES skills(skill_id));-- 프로젝트 정보를 저장하는 테이블CREATE TABLE projects (  project_id INT PRIMARY KEY,  title VARCHAR(255),  start_date DATE,  end_date DATE,  budget DECIMAL(10,2),  description VARCHAR(255),  phase VARCHAR(255));-- 프로젝트와 풀 멤버 간의 관계를 저장하는 테이블 생성CREATE TABLE project_pool_members (  project_id INT,  member_id INT,  PRIMARY KEY (project_id, member_id),  FOREIGN KEY (project_id) REFERENCES projects(project_id),  FOREIGN KEY (member_id) REFERENCES pool_members(member_id));-- 할당되지 않은 프로젝트를 저장하는 테이블CREATE TABLE unassigned_projects (  project_id INT PRIMARY KEY,  title VARCHAR(255),  start_date DATE,  end_date DATE,  budget DECIMAL(10,2),  description VARCHAR(255),  phase VARCHAR(255));-- 할당되지 않은 풀 멤버를 저장하는 테이블CREATE TABLE unassigned_pool_members (  member_id INT PRIMARY KEY,  first_name VARCHAR(255),  last_name VARCHAR(255),  email VARCHAR(255),  phone_number VARCHAR(255),  직장_주소 VARCHAR(255),  home_address VARCHAR(255));```데이터베이스 설계 결정에 대한 설명:1. 데이터베이스 설계는 세 번째 정규 형식(3NF)입니다. 각 테이블은 단일 엔티티를 나타내며 테이블의 모든 열은 해당 엔티티와 직접적으로 연관되어 있습니다.2. 데이터베이스 설계에는 의미 있는 데이터 무결성 제약 조건이 포함되어 있습니다. 각 테이블에 대해 기본 키를 정의하여 각 레코드가 고유한지 확인하고, 외래 키를 사용하여 테이블 간의 참조 무결성을 강화합니다.3. 테이블 간의 관계가 올바르게 정의되도록 적절한 외래 키 제약 조건이 포함되어 있습니다.4. 프로젝트의 요구 사항을 충족하기 위해 아직 프로젝트에 할당되지 않은 프로젝트 및 풀 멤버를 저장하기 위해 unassigned\_projects 및 unassigned\_pool\_members 테이블이 추가되었습니다.5. 요구 사항 R1을 충족하기 위해 프로젝트 테이블은 클라이언트 테이블과 일대다 관계를 갖습니다.6. 요구 사항 R2를 충족하기 위해 project\_pool\_members 테이블은 pool\_members 테이블과 다대다 관계를 갖습니다. project\_pool\_members 테이블의 기본 키는 프로젝트\_id와 멤버\_id라는 두 개의 외래 키로 구성되어 각 풀 멤버가 스킬 요구 사항을 충족하는 경우에만 하나의 프로젝트에 할당될 수 있도록 합니다.7. 요구 사항 R3을 충족하기 위해 member\_skills 테이블은 pool\_members 테이블과 다대다 관계를 갖습니다. 각 스킬에 대한 각 풀 구성원의 다양한 전문성 수준을 파악하기 위해 level\_of\_experience 열이 포함되어 있습니다.8. To