mysql union unique column code example

Example 1: mysql alter table set column unique

ALTER TABLE contacts
ADD CONSTRAINT contacts_unique UNIQUE (reference_number);

Example 2: mysql unique two columns

CREATE TABLE IF NOT EXISTS cliente (
	id bigint primary key auto_increment,
    nome varchar(100) not null,
    email varchar(100) not null unique,
    senha varchar(255) not null,
    documento varchar(50) not null unique,
    dataCadastro date not null
) ENGINE = InnoDB DEFAULT CHARSET = utf8mb4;