EC
1384
MySQLerrorddlhigh confidence

All parts of a PRIMARY KEY must be NOT NULL

Production Risk

Low — DDL fails; no data affected.

What this means

A column included in a PRIMARY KEY definition allows NULL values.

Why it happens
  1. 1Defining a PRIMARY KEY on a nullable column
  2. 2Column default is NULL and PRIMARY KEY is added without first making the column NOT NULL
How to reproduce
trigger — this will error
trigger — this will error
CREATE TABLE t (id INT, PRIMARY KEY (id)); -- id allows NULL by default

expected output

ERROR 1384 (42000): All parts of a PRIMARY KEY must be NOT NULL; if you need NULL in a key, use UNIQUE instead

Fix

Make the PK column NOT NULL

Make the PK column NOT NULL
CREATE TABLE t (id INT NOT NULL, PRIMARY KEY (id));

Why this works

Primary keys require NOT NULL on all component columns.

What not to do

✕

Sources
Official documentation ↗

MySQL 8.0 — 1384 ER_PRIMARY_CANT_HAVE_NULL

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