Squirel SQL uses wrong command for MySQL when renaming a column
OK - the syntax for changing a column name in MySQL is 

ALTER TABLE table_name CHANGE old_col_name new_col_name COL_DATA_TYPE;


However, it appears that the syntax generated by SQuirreL SQL is

ALTER TABLE table_name ALTER COLUMN "old_col_name" RENAME TO "new_col_name";


I tried this with both the MySQL jdbc driver (from mysql.com) and the MariaDB driver (from mariadb.org) and it fails on both counts. 

Indeed using the MySQL contextual menu (just above the Refactoring one you tried to use), it is also impossible to modify the column name.

So, indeed, it appears that you have discovered a bug in SQuirreL SQL. Congratulations!

You can, of course, use the SQL window to perform this operation (tested). 

All I can say is that I'm surprised that SQuirreL SQL has such a flaw for a server as popular as MySQL.