How can Oracle be used to set default values for table fields?

In Oracle, you can use the ALTER TABLE statement to set a default value for a table column. Here is an example:

ALTER TABLE table_name
MODIFY column_name DEFAULT default_value;

In the example above, replace table_name with the name of the table you want to modify, replace column_name with the name of the field you want to set a default value for, and replace default_value with the value you want to set. For example, if you want to set the default value of the field age to 18, you can execute the following statement:

ALTER TABLE employees
MODIFY age DEFAULT 18;