Exploring Tables and Viewing Data
Exploring Database Objects
Querying and Manipulating Data 2-3
Indexes are optional structures that are created to increase the performance of data
retrieval on a table.
Functions are PL/SQL programming objects that can be stored and executed in
the database. Functions return a value.
Procedures are PL/SQL programming objects that can be stored and executed in
the database. Procedures do not return a value.
Packages contains procedures or functions that can be stored and executed in the
database.
Triggers are stored procedures or functions that are associated with a table, view,
or event. Triggers can be called before or after an event for follow-up action, to
prevent erroneous operations, to modify new data so that it conforms to explicit
business rules, or to log a record of an operation or an event.
Types associate a fixed set of properties with the values that can be used in a
column of a table, or in an argument of a procedure or function. Oracle Database
treats values of one data type differently from values of another data type.
Sequences are used to generate unique integers; you can use them to automatically
generate primary key values.
Exploring Tables and Viewing Data
In this section, you will learn how to find out about the properties of database tables,
and how to view the data these tables contain.
An Oracle Database table is its basic data container. All data that a user can access is
inside one of the tables of the database schema. Each table is two-dimensional object
that has rows, which are individual records, and columns, which represent the various
fields of each record.
To view a table:
1.
In Connections navigation hierarchy, click the 'plus' sign next to Tables to expand
the list of tables in the
hr
schema.
The expanded list of tables includes the tables
countries
,
departments
,
employees
,
job_history
,
jobs
,
locations
, and
regions
.
