Most schemas are defaulted to public unless a specific schema is used. To find out what schema to reflect for your datasource, you can run the following query on your database to list all available schemas. Not all databases have this functionality.
select * from pg_namespace;
select schemaname from syscat.schemata
You can leave the schema blank since for MySQL, physically a schema is synonymous with a database.
select USERNAME from SYS.ALL_USERS
select nspname from pg_catalog.pg_namespace
SHOW SCHEMAS [ FROM catalog ]
SELECT * FROM sys.schemas
SELECT table_schema FROM v_catalog.tables
To reflect multiple schemas, refer to Multiple schemas per datasource connection.