They have Java types, whereas the columns of a query have SQL types. SQLJ generates accessor methods for each column of an iterator. SQLJ maintains a connection context and execution context. It supports multiple contexts and concurrent connections to multiple schemas. DB2 includes a sqlj.runtime.
Many applications use a database that is conceptually similar to a spreadsheet's rows and columns.
The schema used for order processing typically includes customer tables, order tables, and product tables. To support historical analysis, we must add a time dimension to the facts in databases. Adding a time dimension produces large multidimensional datasets that, for performance reasons, should be separated from operational data. For decision-support queries, many organizations create separate data marts or data warehouses and feed them with data extracted from operational data stores. Even though we usually segregate OLTP and OLAP data, there is value in staying with the SQL paradigm when we query either type of database.