This is a minimal example that triggers the error

    CREATE TABLE A (

      id bigint NOT NULL AUTO_INCREMENT PRIMARY KEY

    );

    CREATE TABLE B (

      what tinyint NOT NULL,

      a bigint NOT NULL,

      CONSTRAINT x FOREIGN KEY (a) REFERENCES A(id),

      CONSTRAINT y CHECK (what > 0)

    );

    SELECT b.a FROM B b;

    ALTER TABLE B DROP CONSTRAINT x;}}

When i run this in a fresh MariaDB instance (docker mariadb:10.3.28) everything works fine.

When MariaDB 10.3.29 was released the query suddenly broke. So, when i run this in a fresh MariaDB instance (docker mariadb:10.3.29) i get the following error message for the last statement:

[42S22][1054] (conn=8) Unknown column '`db`.`b`.`what`' in 'CHECK'

Some weird observations:

• if i delete the y check and add it after dropping x everything works
• if i remove the SELECT everything works
• if i remove the alias `b` from the `SELECT` statement everything works
• the b from the error message changes with the table alias from the SELECT statement
• running the last statement again shows the same error
• the error message makes no sense at all

I initially posted this on stackexchange https://dba.stackexchange.com/questions/291842/mariddb-10-3-29-prevents-me-from-deleting-a-foreign-key