How to Solve MySQL Error 1062: Duplicate Entry '0' for Key 'PRIMARY' Without Data Loss?

MySQL Error 1062: Crafting a Solution Without Data Loss

In the realm of MySQL, you encounter error 1062: "Duplicate entry '0' for key 'PRIMARY'". This arises when attempting to change the primary key of a table while preserving foreign key relationships and data integrity. To delve into this matter, let us examine the case presented.

The provided query aims to alter the table momento_distribution by adding a new id column as the primary key while retaining its existing relationships. However, the query fails due to duplicate entries in the new primary key.

Analysis reveals that the newly created id column contains the value '0' throughout its rows. As a primary key must contain unique values, this duplication becomes an impediment. To surmount this, we need to configure the id column as auto-increment, ensuring the generation of unique values automatically.

Revised Query for Seamless Execution:

<br>CREATE TABLE momento_distribution<br>  (</p>
<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false"> `id`                 INT(11) NOT NULL AUTO_INCREMENT,
 `momento_id`       INT(11) NOT NULL,
 `momento_idmember` INT(11) NOT NULL,
 `created_at`       DATETIME DEFAULT NULL,
 `updated_at`       DATETIME DEFAULT NULL,
 `unread`           TINYINT(1) DEFAULT '1',
 `accepted`         VARCHAR(10) NOT NULL DEFAULT 'pending',
 `ext_member`       VARCHAR(255) DEFAULT NULL,
 PRIMARY KEY (`momento_id`, `momento_idmember`),
 KEY `momento_distribution_FI_2` (`momento_idmember`),
 KEY `accepted` (`accepted`, `ext_member`)

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)
ENGINE=InnoDB
DEFAULT CHARSET=latin1;

Alternatively, if you already have a id column with values, try this:

<br>ALTER TABLE momento_distribution<br>  CHANGE COLUMN id id INT(11) NOT NULL AUTO_INCREMENT,<br>  DROP PRIMARY KEY,<br>  ADD PRIMARY KEY (id);<br>

With these modifications, MySQL will automatically assign unique values to the new primary key, resolving the duplication issue. Your table structure will be adjusted accordingly, safeguarding your data and ensuring the integrity of your database.

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