sqlÏÈÅÅÐòºó·Ö×éµÄʵÏÖ
ÓÐÕâÑùÒ»¸öÊý¾Ý¿â±í
t1 t2 t3……n
--------------------------
aaa 100 Ê£Óà×Ö¶Î
bbb 80 Ê£Óà×Ö¶Î
aaa 90 Ê£Óà×Ö¶Î
ccc 70 Ê£Óà×Ö¶Î
ccc 500 Ê£Óà×Ö¶Î
ccc 20 Ê£Óà×Ö¶Î
bbb 30 Ê£Óà×Ö¶Î
bbb 40 Ê£Óà×Ö¶Î
bbb 50 Ê£Óà×Ö¶Î
ÎÒÏ£ÍûµÄ×îºó½á¹û¾ÍÊÇ£º
t1 t2 t3……n
------------------
ccc 500 Ê£Óà×Ö¶Î
aaa 100 Ê£Óà×Ö¶Î
bbb 80
Ïà¹ØÎĵµ£º
//°´×ÔÈ»ÖÜͳ¼Æ
select to_char(date,'iw'),sum()
from
where
group by to_char(date,'iw')
//°´×ÔÈ»ÔÂͳ¼Æ
select to_char(date,'mm'),sum()
from
where
group by to_char(date,'mm')
//°´¼¾Í³¼Æ
select to_char(date,'q'),sum()
fr ......
ÔÚSQL SERVERÖУ¬ÓÐʱÐèÒªºÏ¶àÁÐÖµµ½ÐеÄÐèÇ󣬳£¼ûµÄ·½·¨ÓУº1.´´½¨×Ô¶¨Ò庯Êý£¬2.ʹÓÃÓα귨½øÐÐ×Ö·û´®ºÏ²¢¡£3.ʹÓÃÁÙʱ±íʵÏÖ×Ö·û´®ºÏ²¢¡£ Êý¾Ý£º DEPTNO EMPS
------ ----------
10 CLARK
10 KING
10 MILLER
20 SMITH
20 ADAMS
20 FORD
20 SCOTT
20 JONES
30 ALLEN
30 BLAKE
30 MARTIN
30 JAMES
30 ......
value·½·¨
µ±Äã²»Ïë½âÊÍÕû¸ö²éѯµÄ½á¹û¶øÖ»ÏëµÃµ½Ò»¸ö±êÁ¿ÖµÊ±£¬Õâ¸övalue·½·¨ÊǺÜÓаïÖúµÄ¡£Õâ¸övalue·½·¨ÓÃÓÚ²éѯXML²¢ÇÒ·µ»ØÒ»¸öÔ×ÓÖµ¡£
Õâ¸övalue·½·¨µÄÓï·¨ÈçÏ£º
value(XQuery£¬datatype)
½èÖúÓÚvalue·½·¨£¬Äã¿ÉÒÔ´ÓXMLÖеõ½µ¥¸ö±êÁ¿Öµ¡£Îª´Ë£¬Äã±ØÐëÖ¸¶¨XQueryÓï¾äºÍÄãÏëÒªËü·µ»ØµÄÊý¾ÝÀàÐÍ£¬²¢ÇÒÄã¿ÉÒÔ·µ»Ø³ ......
·ÖÒ³sql²éѯÔÚ±à³ÌµÄÓ¦Óúܶ࣬Ö÷ÒªÓд洢¹ý³Ì·ÖÒ³ºÍsql·ÖÒ³Á½ÖÖ£¬ÎұȽÏϲ»¶ÓÃsql·ÖÒ³£¬Ö÷ÒªÊǺܷ½±ã¡£ÎªÁËÌá¸ß²éѯЧÂÊ£¬Ó¦ÔÚÅÅÐò×Ö¶ÎÉϼÓË÷Òý¡£sql·ÖÒ³²éѯµÄÔÀíºÜ¼òµ¥£¬±ÈÈçÄãÒª²é100ÌõÊý¾ÝÖеÄ30-40Ìõ£¬ÄãÏȲéѯ³öÇ°40Ìõ£¬ÔÙ°ÑÕâ30Ìõµ¹Ðò£¬ÔÙ²é³öÕâµ¹ÐòºóµÄÇ°Ê®Ìõ£¬×îºó°ÑÕâÊ®Ìõµ¹Ðò¾ÍÊÇÄãÏëÒªµÄ½á¹û¡£
  ......
¶ÔÓÚ½ñÌìµÄ RDBMS Ìåϵ½á¹¹¶øÑÔ£¬ËÀËøÄÑÒÔ±ÜÃâ — ÔÚ¸ßÈÝÁ¿µÄ OLTP »·¾³ÖиüÊǼ«ÎªÆձ顣ÕýÊÇÓÉÓÚ .NET µÄ¹«¹²ÓïÑÔÔËÐпâ (CLR) µÄ³öÏÖ£¬ SQL Server 2005 ²ÅµÃÒÔΪ¿ª·¢ÈËÔ±ÌṩһÖÖеĴíÎó´¦Àí·½·¨¡£ÔÚ±¾ÔÂרÀ¸ÖУ¬ Ron Talmage ΪÄú½éÉÜÈçºÎʹÓà TRY/CATCH Óï¾äÀ´½â¾öÒ»¸öËÀËøÎÊÌâ¡£
Ò»¸öʾÀýËÀËø
ÈÃÎÒÃÇ´ÓÕâÑùÒ ......