Allow null in unique column

Question

I\'ve created the following table:

CREATE TABLE MMCompany (
   CompanyUniqueID BIGSERIAL PRIMARY KEY NOT NULL, 
   Name VARCHAR (150) NOT NULL,
   PhoneNumb         


        

Answer 1

Drop the email column from the table. Put it in a new table where it can be NOT NULL and UNIQUE:

CREATE TABLE CompanyEmail
 (
    CompanyUniqueID INT NOT NULL PRIMARY KEY
       REFERENCES MMCompany (CompanyUniqueID),
    Email VARCHAR(75) NOT NULL UNIQUE
 );

Avoid nullable UNIQUE constraints.