Date Conversion

Dates are converted to numbers by calculating the Julian date, the (integer) number of days that have elapsed since January 1, 4712 BCE. The calculation used by Oracle results in a seven-digit number (for dates most often used), such as 2449086 for 08-APR-93.

The following SQL illustrates how the conversion is performed:

TO_NUMBER(TO_CHAR( "CUSTOMERS"."CUST_EFF_FROM", 'J')) AS "CUST_EFF_FROM"

For more information about Julian dates, see the discussion of the DATE datatype in Oracle Database Concepts.