msql_fetch_field() can be used in order to obtain information about fields in a certain query result.
返回类型为 resource 的结果集。该结果集从 msql_query() 的调用中得到。
The field offset. If not specified, the next field that wasn't yet retrieved by msql_fetch_field() is retrieved.
Returns an object containing field information. The properties of the object are:
name - column name
table - name of the table the column belongs to
not_null - 1 if the column cannot be
unique - 1 if the column is a unique key