A schemaName represents a schema. Schemas contain other dictionary objects, such as tables and indexes. Schemas provide a way to name a subset of tables and other dictionary objects within a database.
You can explicitly create or drop a schema. The default user schema is the APP schema (if no user name is specified at connection time). You cannot create objects in schemas starting with SYS.
Thus, you can qualify references to tables with the schema name. When a schemaName is not specified, the default schema name is implicitly inserted. System tables are placed in the SYS schema. You must qualify all references to system tables with the SYS schema identifier. For more information about system tables, see Derby system tables.
A schema is hierarchically the highest level of dictionary object, so you cannot qualify a schemaName.
SQLIdentifier
-- SAMP.EMPLOYEE is a tableName qualified by a schemaName SELECT COUNT(*) FROM SAMP.EMPLOYEE -- You must qualify system table names with their schema, SYS SELECT COUNT(*) FROM SYS.SysColumns