Can we
directly update the GL_DAILY_RATES table?
No.
Directly updating any base table is not recommended and any changes in the
table should come through the daily rates interface table only -
GL_DAILY_RATES_INTERFACE.
Insert
rows into it with a FROM_CURRENCY, a TO_CURRENCY, a FROM_CONVERSION_DATE, a
TO_CONVERSION_DATE, a USER_CONVERSION_TYPE, a dummy CONVERSION_RATE, and a MODE
of ’D’.

