Abstract Data Types in SQL3

• Row types provide a lot of the functionality of objects:

• allow us to modify objects (unlike OQL), but
• do not provide encapsulation.
  • We can modify objects arbitrarily using SQL3 commands.
  • In OQL: we can query, but not modify only via methods.

• Abstract data types: are used as components of tuples.

CREATE TYPE <type name> (

list of attributes and their types

optional declaration of the comparison functions: =, <

declaration of methods for the type

);

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