mysql_field_flags() returns the
field flags of the specified field. The flags are reported as
a single word per flag separated by a single space, so that
you can split the returned value using
explode().
The following flags are reported, if your version of MySQL
is current enough to support them: "not_null", "primary_key",
"unique_key", "multiple_key", "blob", "unsigned", "zerofill",
"binary", "enum", "auto_increment", "timestamp".
For downward compatibility
mysql_fieldflags() can also be used. This is deprecated,
however.