Creator column: The Creator column shows which user created a table.
TName column: The Tname column contains the names of the tables in the database.
DBSpace: The DBSpace column shows where each table is stored on the computer.
TableType: The TableType column shows the type of each table (e.g., base table, temporary table).
Ncols: The number of columns in a table.
PrimaryKey: Whether the table has a primary key field or fields.
Sample Data Dictionary Tables
The precise tables that make up a data dictionary depend somewhat on the DBMS.
The keystone of the data dictionary is actually a table that documents all the data dictionary tables (often named syscatalog, the first few rows
of which can be found in Figure 6-16). From the names of the data dictionary tables, you can probably guess that there are tables to store data about base tables, their columns, their indexes, and their foreign keys.