OCIBindByName() binds the PHP variable variable to the Oracle placeholder ph_name. Whether it will be used for input or output will be determined run-time, and the necessary storage space will be allocated. The length paramter sets the maximum length for the bind. If you set length to -1 OCIBindByName() will use the current length of variable to set the maximum length.
If you need to bind an abstract Datatype (LOB/ROWID/BFILE) you need to allocate it first using OCINewDescriptor() function. The length is not used for abstract Datatypes and should be set to -1. The type variable tells oracle, what kind of descriptor we want to use. Possible values are: OCI_B_FILE (Binary-File), OCI_B_CFILE (Character-File), OCI_B_CLOB (Character-LOB), OCI_B_BLOB (Binary-LOB) and OCI_B_ROWID (ROWID).