Returns precision of the field with field index (1-based).
For FLOAT columns, precision is nonzero and scale is -127. If precision is 0, then column is NUMBER. Else it's NUMBER(precision, scale).
Note: In PHP versions before 5.0.0 you must use ocicolumnprecision() instead. This name still can be used, it was left as alias of oci_field_precision() for downwards compatability. This, however, is deprecated and not recommended.
See also oci_field_scale() and oci_field_type().