Designing a database structure for companies and stock owners

-- You have to determine which are the most fitting 
-- data types and sizes for all the table columns 
-- depending on the business context characteristics.

-- Also, you should make accurate tests to define the
-- most convenient physical implementation settings; e.g.,
-- a good INDEXing strategy based on query tendencies.

-- As one would expect, you are free to make use of 
-- your preferred (or required) naming conventions.

CREATE TABLE Company ( -- Stands for an independent entity type
    CompanyId       INT       NOT NULL, -- You may like to set it with the SERIAL type to retain system-assigned and system-generated surrogate values.
    Name            TEXT      NOT NULL,
    FoundingDate    DATE      NOT NULL,
    Etcetera        TEXT      NOT NULL,
    CreatedDateTime TIMESTAMP NOT NULL DEFAULT NOW(), -- You may also configure it so that the DEFAULT value is set by the CURRENT_TIMESTAMP function, if appropriate. 
    --
    CONSTRAINT Company_PK PRIMARY KEY (CompanyId),
    CONSTRAINT Company_AK UNIQUE      (Name) -- Single-colum ALTERNATE KEY.
);

CREATE TABLE Person ( -- Denotes an independent entity type.
    PersonId        INT       NOT NULL, -- You may like to set it with the SERIAL type to retain system-assigned and system-generated surrogate values.
    FirstName       TEXT      NOT NULL,
    LastName        TEXT      NOT NULL,
    GenderCode      TEXT      NOT NULL,
    BirthDate       DATE      NOT NULL,
    BirthPlace      TEXT      NOT NULL,  
    Address         TEXT      NOT NULL,   
    PhoneNumber     TEXT      NOT NULL,     
    CreatedDateTime TIMESTAMP NOT NULL DEFAULT NOW(), -- You may also configure it so that the DEFAULT value is set by the CURRENT_TIMESTAMP function, if appropriate.
    --
    CONSTRAINT Person_PK PRIMARY KEY (PersonId),
    CONSTRAINT Person_AK UNIQUE      ( -- Composite ALTERNATE KEY.
        FirstName,
        LastName,
        GenderCode,
        BirthDate,
        BirthPlace
    )
);

CREATE TABLE CompanyOwner ( -- Represents an associative entity type or M:N association. Attaching an extra column to hold system-generated and system-assigned surrogate values to this table is superfluous.
    CompanyId          INT       NOT NULL,
    OwnerId            INT       NOT NULL,
    StockShareQuantity INT       NOT NULL,
    Etcetera           TEXT      NOT NULL,  
    CreatedDateTime    TIMESTAMP NOT NULL DEFAULT NOW(), -- You may also configure it so that the DEFAULT value is set by the CURRENT_TIMESTAMP function, if appropriate. 
    --
    CONSTRAINT CompanyOwner_PK          PRIMARY KEY (CompanyId, OwnerId), -- Composite PRIMARY KEY.
    CONSTRAINT CompanyOwnerToCompany_FK FOREIGN KEY (CompanyId)
        REFERENCES Company (CompanyId),
    CONSTRAINT CompanyOwnerToPerson_FK  FOREIGN KEY (OwnerId)
        REFERENCES Person (PersonId),
    CONSTRAINT StockShareQtyIsValid_CK  CHECK       (StockShareQuantity >= 0) -- Appears to be required.
);

INSERT INTO Company 
    (CompanyId, Name, FoundingDate, Etcetera)
VALUES
    (1748, 'Database Modeling Inc.', '1985-06-30', 'Foo'),
    (1750, 'Application Programming Co.', '1987-10-14', 'Bar');

INSERT INTO Person 
    (PersonId, FirstName, LastName, BirthDate, BirthPlace, GenderCode, Address, PhoneNumber)
VALUES
    (1, 'Edgar', 'Codd', '1923-08-19', 'Fortuneswell, UK', 'M', 'IBM Research Laboratory K01/282, 5600 Cottle Road, San Jose, CA, USA', '01-800-17-50-17-50'),
    (2, 'Alan', 'Turing', '1912-06-23', 'Maida Vale, UK','M', 'National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, England', '01-800-17-48-17-48'),
    (3, 'Grace', 'Hopper', '1906-12-09', 'New York City, USA', 'F', 'Navy’s Office of Information Systems Planning, USA.', '01-800-17-50-17-50'),   
    (4, 'Diego', 'Velázquez', '1599-06-06', 'Seville, Spain', 'M', 'Palacio Real, Madrid, Spain', '01-800-17-50-17-50'),
    (5, 'Michelangelo', 'Buonarroti', '1475-03-06', 'Caprese, Italy', 'M', 'Sistine Chapel, Vatican City State', '01-800-17-50-17-50'); 

INSERT INTO CompanyOwner 
    (CompanyId, OwnerId, StockShareQuantity, Etcetera)
VALUES
    (1748, 1, 2500, 'U'),
    (1750, 1, 2500, 'V'),
    (1750, 2, 8000, 'W'),
    (1750, 3, 3580, 'X'),
    (1748, 4, 12899, 'Y'),
    (1750, 5, 12899, 'Z');

CREATE VIEW CompanyAndOwner AS
    SELECT C.CompanyId,
           C.Name AS CompanyName,
           P.PersonId,
           P.FirstName,
           P.LastName,
           P.BirthDate,
           P.BirthPlace,
           P.GenderCode,
           P.Address,
           P.PhoneNumber,
          CO.StockShareQuantity,
           P.CreatedDateTime
        FROM Person P
        JOIN CompanyOwner CO
          ON CO.OwnerId = P.PersonId
        JOIN Company C
          ON C.CompanyId = CO.CompanyId;

SELECT *            
  FROM CompanyAndOwner 
 WHERE CompanyId = 1750;

SELECT CompanyName,
       FirstName AS OwnerFirstName,
       LastName  AS OwnerLastName,
       StockShareQuantity
  FROM CompanyAndOwner 
 WHERE CompanyId = 1750;