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There are various ways you can assist the user with
data entry. For example, you can create an expression using arithmetic operators. You can create an
expression when creating the table.
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To create an expression when creating a table, provide
the name of the
column, type AS, open a parenthesis, type the
desired expression, and close the parenthesis. Here is an example:
SQL> CREATE TABLE Circle
2 (
3 Radius number(8, 3),
4 Area AS (Radius * Radius * 3.14159)
5 );
Table created.
When performing data entry, you must not provide a
value for a column that has an expression. Here is an example of entering data for
the above Circle table:
SQL> INSERT INTO Circle(Radius) VALUES(46.82);
1 row created.
SQL> SELECT * FROM Circle;
RADIUS AREA
---------- ----------
46.82 6886.71839
SQL>
