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Data dictionary tables

Syscatalog

SYSCATALOG data dictionary table
The SYSCATALOG data dictionary table.
  1. Creator column: The Creator column shows which user created a table.
  2. TName column: The Tname column contains the names of the tables in the database.
  3. DBSpace: The DBSpace column shows where each table is stored on the computer.
  4. TableType: The TableType column shows the type of each table (e.g., base table, temporary table).
  5. Ncols: The number of columns in a table.
  6. 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.

Figure 6-16: Syscatalog consisting of 1) creator 2) tname 3) dbspace 3) tabletype 4) ncols 5) Primary_key