Dual Primary Keys in MySQL: A Simple Guide

1 year ago
Ava Mitchell
1 minute

In MySQL, primary keys are typically used to uniquely identify each row of data in a table. If you want to set up a table with dual primary keys, you need to create a composite key. This means that you will need to designate two or more columns as the primary key, rather than just one column.

Here is the process of setting up dual primary keys in MySQL:

  1. people
  2. user handle
  3. send an email
CREATE TABLE users (
    username VARCHAR(255),
    email VARCHAR(255),
    PRIMARY KEY (username, email)
);

In the example above, the columns username and email are defined together as the primary key.

  1. Change the structure of the table
  2. individuals who use the platform
  3. user ID
  4. Send an email.
ALTER TABLE users
ADD PRIMARY KEY (email);

In the example above, the email column was added as another primary key.

Please note that when setting composite primary keys, ensure that the combination of columns is unique, otherwise errors will occur. You can also set other constraints such as foreign key constraints or unique constraints to ensure data integrity and consistency.

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