update xempl set ddentree = adddate(ddentree, interval 16 year);
  The same value sdval was used to convert MySQL dates to CONNECT date
  value and CONNECT dates to MySQL date. This was wrong in update because
  the second time the wrong value was used converting to incoherent values.
  There are now 2 separate values used: sdvalin and sdvalout.

modified:
  storage/connect/ha_connect.cc
  storage/connect/ha_connect.h