For example, we pointed out that the
Oracle instance differs from the files that make up the physical storage of the data in
tablespaces, that youcannot access the data in a tablespace except through an Oracle
instance, and that the instance itself isn??™t very valuable without the data stored in
those files.
The instance is the logical entity used by applications and users, separate from the
physical storage of data. In a similar way, the actual tables and columns are logical
entities within the physical database. The user who makes a request for data from an
Oracle database probably doesn??™t know anything about instances and tablespaces, but
does know about the structure of her data, as implemented with tables and columns.
To fully leverage the power of Oracle, you must understand how the Oracle database
server implements and uses these logical data structures, the topic of this chapter.
Datatypes
The datatype is one of the attributes for a column or a variable in a stored procedure.
A datatype describes and limits the type of information stored in a column, and can
limit the operations that you can perform on columns.
Pages:
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197