A data type associates 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. These properties cause Oracle Database to treat values of one data type differently from values of another data type. For example, Oracle Database can use the addition operator on values of NUMBER data type, but not with values of some other data types. The data types supported by Oracle Database include characters, numbers, and dates and times (known as datetime data types).
To view the data types contained in a database table, such as the employees table, you can use Connections navigator or the SQL*Plus DESCRIBE. For information on the SQL*Plus DESCRIBE command, see SQL*Plus DESCRIBE Command.