SQL-ORDER BY 多字段排序(升序、降序)

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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 /