The complete structure definition has to be listed inside the declare
section of the structure variable for ecpg to be able to understand it.

Variable type bool has to be tested. I never used it so far.

The error message for "no data" in an exec sql insert select from statement
has to be 100.

sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified in a SET
DESCRIPTOR statement will be ignored.

it would be nice to be able to use :var[:index] as cvariable

Missing statements:
 - exec sql type
 - exec sql define
 - exec sql prepare
 - exec sql allocate
 - exqc sql free
 - SQLSTATE
 - exec sql whenever sqlwarning
