MySQL 5.6 C API Developer Guide
MYSQL_FIELD * mysql_fetch_field_direct(MYSQL_RES *result, unsigned int fieldnr)
Given a field number fieldnr
for a column
within a result set, returns that column's field definition as
a MYSQL_FIELD
structure. Use this function
to retrieve the definition for an arbitrary column. Specify a
value for fieldnr
in the range from 0 to
mysql_num_fields(result)-1
.