MySQL Refuses a Plain DEFAULT Value on TEXT Columns

A notes column declared as TEXT DEFAULT '' works on SQLite, PostgreSQL and MariaDB. MySQL refuses the CREATE TABLE.

MySQL 8.0.13 and later accept a default written as an expression in parentheses, DEFAULT ('a'), which the other three engines accept as well.

What Each Engine Answered

The example

CREATE TABLE t (id INTEGER, x TEXT DEFAULT 'a');
INSERT INTO t (id) VALUES (1);
SELECT x FROM t;

gave these answers:

What to Write Instead

This form answers the same on every engine:

CREATE TABLE t (id INTEGER, x TEXT DEFAULT ('a'));
INSERT INTO t (id) VALUES (1);
SELECT x FROM t;

Put the default in parentheses, DEFAULT ('a'), or use VARCHAR(n).

What BareSQL Portable Reports

Saved as example.sql, the example gets this from baresql lint --all:

$ baresql lint --all example.sql
example.sql:1:36: error: MySQL refuses a plain DEFAULT value on TEXT, BLOB and JSON columns; SQLite, PostgreSQL and MariaDB accept it. [text-default]
    DEFAULT 'a'
    Put the default in parentheses, DEFAULT ('a'), or use VARCHAR(n).

1 problem: 1 error.

baresql rules text-default prints the same answers in the terminal, and the BareSQL Portable page lists every difference BareSQL knows.