This simple statement fails to create the column. This has been reported in the past and still not fixed.
ALTER TABLE esq.event ADD COLUMN LINK_TABLE_REF VARCHAR(3) DEFAULT GENERATED ALWAYS AS 'eat';
~~~~ ERROR ~~~~~
12:55:11 [ALTER - 0 row(s), 0.000 secs] [Error Code: 30000, SQL State: 42X01] Syntax error: Encountered "GENERATED" at line 1, column 68.
The error message comes from the database, not from DbVisualizer. Please double-check that GENERATED ALWAYS is supported by the database you use.
Or do you mean that this ALTER statement is generated by the Alter Table dialog in DbVisualizer? If so, please tell us which database type you use. Best would be if you connect to the database, open Help->Contact Support and copy the info from the Application Properties area into your reply.