It appears the class constants only cover PDO::PARAM_BOOL, PDO::PARAM_INT and PDO::PARAM_STR for binding. Do you just bind decimal / f
PDO::PARAM_BOOL
PDO::PARAM_INT
PDO::PARAM_STR
If you really want to use PDO you'll have to enter it as an PARAM_INT, but I never use a specification for double.
PARAM_INT
double
It is an optional parameter to specify the PDO type.
PDO
I guess you would better not set the PDO type for doubles.