TODO

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

it would also be nice to be able to work with varchar * (inculding automatic
allocating)

support for dynamic SQL with unknown number of variables with SQLDA structure
or something similar

Missing statements:
 - exec sql allocate
 - SQLSTATE