My queries are managed by a
SET MYDATETIME = :myDateTime
WHERE (MYKEY = :myKey)
ORA-01840: Input value not long enough for date format
As per comment chat, it seems that a string conversion is occurring because the parameter database type is set to varchar
Set the ProviderType of the parameter to be something more relevant to the type Oracle is expecting - it'll either be Date, DateTime, Timestamp, OracleDateTime or some variation on this theme (the names change according to whether you use .net oracle client or oracle's one) , hopefully...