Depends exactly what you mean.
If you want to generate the DDL that corresponds to an existing schema, see 'show create table' and/or mysqldump
If you have the schema design in another format eg text, then you'll need to write a prog eg Perl to parse that to create the DDL.
Note that most (all?) schema design tools usually have a built-in fn or associated tool that will do that for you.
It may or may not be MySQL compatible if the tool is designed eg for Oracle