According to Oracle Metalink Bug Database Doc ID: 144784.1, in the absence of explicit data typecasting, OCI assumes that a bind variable is a CHAR data type. If the SQL statement intends to use the bind variable as a DATE data type, but OCI thought it was a CHAR, the SQL parser will have a conflict in data types. The fix is to explicitly use data conversion functions to convert the bind variables in the problem queries. For example, a select string of

String st = "select count(*) from simple_table where

TRUNC(mydate) = TRUNC(?)";

should be changed to:

String st = "select count(*) from simple_table where

TRUNC(mydate) = TRUNC(TO_DATE(?))";