MySQL 5.7 C API Developer Guide / ... / C API Prepared Statement Interface / C API Prepared Statement Function Descriptions / mysql_stmt_row_tell()
MYSQL_ROW_OFFSETmysql_stmt_row_tell(MYSQL_STMT *stmt) Returns the current position of the row cursor for the lastmysql_stmt_fetch(). This value can be used as an argument tomysql_stmt_row_seek().
You should usemysql_stmt_row_tell() only aftermysql_stmt_store_result().