All MySQL error codes

MySQL error code

MySQL error 1242

MySQL server error 1242 is ER_SUBQUERY_NO_1_ROW, reported with SQLSTATE 21000.

Subquery returns more than 1 row

Error	1242
Name	ER_SUBQUERY_NO_1_ROW
SQLSTATE	21000
Group	Server errors

How to fix it

Explained step by step, with a query you can run

more than one row returned by a subquery used as an expression

In other databases

Source: MySQL 8.4 Error Reference