Database Reference
In-Depth Information
Java is a better option. Database modeling is an even deeper layer than PL/
SQL for a relational database. Therefore, building object structures in a
relational database is somewhat counterintuitive because object applications
and particularly object databases thrive on complex structures. Relational
databases can collapse in a pile of rubble in complex environments but
thrive on simplicity. How many of us have seen ERDs (Entity Relationship
Diagrams) covering the entire wall of an office? In a relational database,
complexity usually leads to more complexity, and so on, ad infinitum.
20.2.2
CREATE VIEW Syntax
Constraint syntax for the CREATE VIEW command is shown in Figure
20.7. The way in which constraints are handled for the CREATE VIEW
command is the same as for the CREATE TABLE command. As a result,
no examples in addition to those in Chapter 19 are required in this chapter.
See Chapter 19 for details.
20.3
Adding, Modifying, and Dropping Constraints
20.3.1
ALTER TABLE Syntax
Let's begin with the ALTER TABLE command syntax including only con-
straint details. The syntax diagram is shown in Figure 20.8. Examining Fig-
ure 20.8, we can see that constraints can be renamed, modified, added new,
or dropped using the ALTER TABLE syntax.
Figure 20.7
CREATE VIEW
Constraints Syntax.
Search WWH ::




Custom Search