Introduction to Data Management

Accessing Databases With NonStop SQL
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Figure 3-4. Structural Levels in a Database
S8020-010
Logical Level
Physical Level
Views
Views
Tables
Files
NonStop SQL also lets you explicitly request the locking of entire tables or rows
within a table. With this feature, you can control the degree to which you protect
your data from access by concurrent users. This control, though, is subject to a trade-
off. In general, the more you protect your data from access by concurrent users, the
greater the level of database consistency you gain but the slower your application
runs.