SQL-ORDER BY 多字段排序(升序、降序)

order by _column1, _column2; /* _column1升序，_column2升序 */ 

order by _column1, _column2 desc; /* _column1升序，_column2降序 */ 

order by _column1 desc, _column2 ; /* _column1降序，_column2升序 */ 

order by _column1 desc, _column2 desc; /* _column1降序，_column2降序 */