ªð¦^¦Cªí ¤W¤@¥DÃD µo©«

[¤À¨É] NULL­È±Æ§Ç¤è¦¡

[¤À¨É] NULL­È±Æ§Ç¤è¦¡

ORDER BY col DESC NULLS FIRST --NULL­È±Æ¦b³Ì«e­± ¨ä¥L¼Æ­È¥¿¦V±Æ¦C
ORDER BY col ASC NULLS FIRST --NULL­È±Æ¦b³Ì«e­± ¨ä¥L¼Æ­È¤Ï¦V±Æ¦C

ORDER BY col DESC NULLS FIRST --NULL­È±Æ¦b³Ì«e­± ¨ä¥L¼Æ­È¥¿¦V±Æ¦C
ORDER BY col ASC NULLS FIRST --NU ...
Min µoªí©ó 2010-5-9 20:52



    ½Ð°Ý¤p¶{ª©¥D
¦pªG¥t¥~¦Û³]¥["is not null"±ø¥ó¡A¹F¨ì¨Ï¥Î(ORDER BY)  Indexªº­n¨D¡K¡K
¬O§_¥i¥H©¿²¤
ORDER BY col DESC NULLS FIRST --NULL­È±Æ¦b³Ì«e­± ¨ä¥L¼Æ­È¥¿¦V±Æ¦C
ORDER BY col ASC NULLS FIRST --NULL­È±Æ¦b³Ì«e­± ¨ä¥L¼Æ­È¤Ï¦V±Æ¦C
¥¿¤Ï¦V(¤É§Ç©Î­°§Ç±Æ¦C)?
ÁÂÁÂ!!

TOP

¬JµM¬O¤U±ø¥ó±Æ°£null (is not null)
¨º´Nª½±µ¼g order by col ...
³o¼Ë´N¥i¥H±Æ§Ç¤F~
­Y¬O§Ú¦^µª¡A¨Ï±zº¡·N¡A½Ð±zÅý§Úª¾¹D¡I                  
­Y¬O§Úªº¦^ÂСA±z¤´¦³¨ä¥L¨£¸Ñ¡A¤]½Ð±z¤£¶Þ«ü±Ð¡I

TOP

        ÀR«ä¦Û¦b : ºw¤ô¦¨ªe¡C²É¦Ì¦¨ÅÚ¡A¤Å»´¤vÆF¡A¤Å¥Hµ½¤p¦Ó¤£¬°¡C
ªð¦^¦Cªí ¤W¤@¥DÃD