How to Fix MySQL Error 1062: Duplicate Entry for Key \'PRIMARY\'?

MySQL Error 1062: Resolving "Duplicate Entry for Key 'PRIMARY'"

An "Error Code: 1062. Duplicate entry '1' for key 'PRIMARY'" occurs when attempting to insert duplicate values into a column marked as a primary key. This ensures data integrity by preventing rows with identical primary key values.

In the provided example, the UFFICIO-INFORMAZIONI table has an ID column defined as the primary key. When attempting to insert a new record with an ID of 1, the error occurs because that value already exists in the table.

Solution:

The primary key constraint requires unique values in the specified column. To resolve the error, you can make the ID column auto-increment by replacing the table definition with the following:

CREATE TABLE IF NOT EXISTS `PROGETTO`.`UFFICIO-INFORMAZIONI` (
  `ID` INT(11) NOT NULL AUTO_INCREMENT,
  `viale` VARCHAR(45) NULL,
  ...

When inserting records, you can now omit the ID column, allowing the database to automatically generate unique values:

INSERT INTO `PROGETTO`.`UFFICIO-INFORMAZIONI` (`viale`, `num_civico`, ...)
VALUES ('Viale Cogel ', '120', ...)

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