Query below lists schemas in database created by users, i.e. excluding default SYS*, SQLJ, and NULLID schemas.
Use this query to list all schemas.
Query
select schemaname as schema_name,
    owner as schema_owner,
    case ownertype 
        when 'S' then 'system'
        when 'U' then 'individual user' 
    end as schema_owner_type,
    definer as schema_definer,
    case definertype 
        when 'S' then 'system'
        when 'U' then 'individual user'
    end as schema_definer_type
from syscat.schemata    
where schemaname not like 'SYS%'
and  schemaname not IN ('SQLJ', 'NULLID')
order by schema_name
Columns
- schema_name - schema name
- schema_owner - authorization ID of the owner of the schema
- schema_owner_type - owner type:
- system
- individual user
 
- schema_definer - authorization ID of the definer of the schema
- schema_definer_type - definer type
- system
- individual user
 
Rows
- One row represents one schema in a database
- Scope of rows: all schemas in a database, excluding default SYS* , SQLJ, NULLID
- Ordered by schema name
Sample results

 
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                     
                                                                 
                                                             
                                                             
                                                             
                                                             
                                                                 
                                                             
                                                             
                                                                 
                                                             
                                                             
                                                             
                                                             Marcin Nagly
                                                                        Marcin Nagly
                                 IBM Db2
                                                                IBM Db2
                                 SQL Server
                                                                                                SQL Server
                                             Azure SQL Database
                                                                                                Azure SQL Database
                                             Snowflake
                                                                                                Snowflake
                                             Amazon Redshift
                                                                                                Amazon Redshift
                                             Vertica
                                                                                                Vertica
                                             PostgreSQL
                                                                                                PostgreSQL
                                             MySQL
                                                                                                MySQL
                                             MariaDB
                                                                                                MariaDB