this is some simple code but I just don\'t know why I can\'t use this word as the entity of the table
CREATE TABLE IF NOT EXISTS users( key INT PRIMARY KEY N
Simple solution: Add a trailing underscore to every name.
The SQL spec SQL:2011 explicitly promises to never use a trailing underscore on any keyword, neither now nor in the future.
Example: key_
key_
See my answer to a similar question, h2 database column name is reserved word.