Translate the following question to SQL: List the employees who have not showed up in any circulation history of documents. List the employee's name.

Schema: CREATE TABLE Ref_Document_Types (
    document_type_code CHAR(15) NOT NULL  PRIMARY KEY,
    document_type_description VARCHAR(255) NOT NULL,
    UNIQUE (document_type_code)
);

CREATE TABLE Roles (
    role_code CHAR(15) NOT NULL  PRIMARY KEY,
    role_description VARCHAR(255),
    UNIQUE (role_code)
);

CREATE TABLE Addresses (
    address_id INTEGER NOT NULL  PRIMARY KEY,
    address_details VARCHAR(255)
);

CREATE TABLE Ref_Document_Status (
    document_status_code CHAR(15) NOT NULL  PRIMARY KEY,
    document_status_description VARCHAR(255) NOT NULL,
    UNIQUE (document_status_code)
);

CREATE TABLE Ref_Shipping_Agents (
    shipping_agent_code CHAR(15) NOT NULL  PRIMARY KEY,
    shipping_agent_name VARCHAR(255) NOT NULL,
    shipping_agent_description VARCHAR(255) NOT NULL,
    UNIQUE (shipping_agent_code)
);

CREATE TABLE Documents (
    document_id INTEGER NOT NULL  PRIMARY KEY,
    document_status_code CHAR(15) NOT NULL,
    document_type_code CHAR(15) NOT NULL,
    shipping_agent_code CHAR(15),
    receipt_date DATETIME,
    receipt_number VARCHAR(255),
    other_details VARCHAR(255),
    FOREIGN KEY (shipping_agent_code) REFERENCES Ref_Shipping_Agents(shipping_agent_code),
    FOREIGN KEY (document_status_code) REFERENCES Ref_Document_Status(document_status_code),
    FOREIGN KEY (document_type_code) REFERENCES Ref_Document_Types(document_type_code)
);

CREATE TABLE Employees (
    employee_id INTEGER NOT NULL  PRIMARY KEY,
    role_code CHAR(15) NOT NULL,
    employee_name VARCHAR(255),
    other_details VARCHAR(255),
    FOREIGN KEY (role_code) REFERENCES Roles(role_code)
);

CREATE TABLE Document_Drafts (
    document_id INTEGER NOT NULL  PRIMARY KEY,
    draft_number INTEGER NOT NULL  PRIMARY KEY,
    draft_details VARCHAR(255),
    PRIMARY KEY (document_id, draft_number),
    UNIQUE (document_id, draft_number),
    FOREIGN KEY (document_id) REFERENCES Documents(document_id)
);

CREATE TABLE Draft_Copies (
    document_id INTEGER NOT NULL  PRIMARY KEY,
    draft_number INTEGER NOT NULL  PRIMARY KEY,
    copy_number INTEGER NOT NULL  PRIMARY KEY,
    PRIMARY KEY (document_id, draft_number, copy_number),
    UNIQUE (document_id, draft_number, copy_number),
    FOREIGN KEY (document_id) REFERENCES Document_Drafts(document_id),
    FOREIGN KEY (draft_number) REFERENCES Document_Drafts(draft_number)
);

CREATE TABLE Circulation_History (
    document_id INTEGER NOT NULL  PRIMARY KEY,
    draft_number INTEGER NOT NULL  PRIMARY KEY,
    copy_number INTEGER NOT NULL  PRIMARY KEY,
    employee_id INTEGER NOT NULL  PRIMARY KEY,
    PRIMARY KEY (document_id, draft_number, copy_number, employee_id),
    UNIQUE (document_id, draft_number, copy_number, employee_id),
    FOREIGN KEY (employee_id) REFERENCES Employees(employee_id),
    FOREIGN KEY (document_id) REFERENCES Draft_Copies(document_id),
    FOREIGN KEY (draft_number) REFERENCES Draft_Copies(draft_number),
    FOREIGN KEY (copy_number) REFERENCES Draft_Copies(copy_number)
);

CREATE TABLE Documents_Mailed (
    document_id INTEGER NOT NULL  PRIMARY KEY,
    mailed_to_address_id INTEGER NOT NULL  PRIMARY KEY,
    mailing_date DATETIME,
    PRIMARY KEY (document_id, mailed_to_address_id),
    UNIQUE (document_id, mailed_to_address_id),
    FOREIGN KEY (mailed_to_address_id) REFERENCES Addresses(address_id),
    FOREIGN KEY (document_id) REFERENCES Documents(document_id)
);
user
SELECT employee_name FROM Employees EXCEPT SELECT Employees.employee_name FROM Employees JOIN Circulation_History ON Circulation_History.employee_id = Employees.employee_id
assistant