SQLµÝ¹é²éѯÊý¾Ý
Tree±íÈçÏÂ:
NodeId ParentId NodeName
0 -1 Ò»
1 0 ¶þ
9 1 Èý
10 9 ËÄ
12 10 Îå
18 1 Áù
ÒÑÖª£ºNodeid Äܵõ½ NodeName µÄµÝ¹éÁ¬½Ó×Ö·û´®Âð£¿
Àý£º ÒÑÖª ½á¹û
NodeId:10 ËÄÈý¶þÒ»
NodeId:18 Áù¶þÒ»
NodeId:1 ¶þÒ»
½â¾ö·½·¨£º
1¡¢´´½¨±í½á¹¹¡£
³ÌÐò´úÂë
create table Tree(NodeId int,Paren
Ïà¹ØÎĵµ£º
Ö÷¼ü:
Äܹ»Î¨Ò»±íʾÊý¾Ý±íÖеÄÿ¸ö¼Ç¼µÄ¡¾×ֶΡ¿»òÕß¡¾×ֶΡ¿µÄ×éºÏ¾Í³ÆÎªÖ÷Âë(Ö÷¼ü)¡£ Ò»¸öÖ÷¼üÊÇΨһʶ±ðÒ»¸ö±íµÄÿһ¼Ç¼£¬µ«ÕâÖ»ÊÇÆä×÷ÓõÄÒ»²¿·Ö£¬Ö÷¼üµÄÖ÷Òª×÷ÓÃÊǽ«¼Ç¼ºÍ´æ·ÅÔÚÆäËû±íÖеÄÊý¾Ý½øÐйØÁª¡£ÔÚÕâÒ»µãÉÏ£¬Ö÷¼üÊDz»Í¬±íÖи÷¼Ç¼֮¼äµÄ¼òµ¥Ö¸Õë¡£Ö÷¼üÔ¼Êø¾ÍÊÇÈ·¶¨±íÖеÄÿһÌõ¼Ç¼¡£Ö÷¼ü²»ÄÜÊÇ¿ÕÖµ¡£Î¨Ò ......
±íÖÐÖ÷¼ü±ØÐëΪ±êʶÁУ¬[ID] int IDENTITY (1,1)
1.·ÖÒ³·½°¸Ò»£º(ÀûÓÃNot InºÍSELECT TOP·ÖÒ³)
Óï¾äÐÎʽ£º
SELECT TOP Ò³¼Ç¼ÊýÁ¿ *
from ±íÃû
WHERE (ID NOT IN
(SELECT TOP (ÿҳÐÐÊý*(Ò³Êý-1)) ID
from ±íÃû
ORDER BY ID))
ORDER BY ID
//×Ô¼º»¹¿ÉÒÔ¼ÓÉÏһЩ²é ......
ÊäÈë: select ID as ±àºÅ, NAME as ÐÕÃû, AGE as ÄêÁä from XXX
Êä³ö:
񅧏
ÐÕÃû
ÄêÁä
ÒªÇóÊÇÈç¹ûSQL±ä¶¯, ÈÔȻҪÏÔʾ³öÀ´ËùÓеıðÃû×Ö¶ÎÐÅÏ¢ºÍÊý¾Ý.
ÒòΪÏÖÔÚHibernateÓõıȽϹ㷺, ËùÒÔÓÅÏÈ¿¼ÂÇÓÃHibernateÀ´ÊµÏÖ, ½á¹û·¢ÏÖÈç¹ûÊÇʵÌåÓ³Éä²éѯÓï¾ä, ¿ÉÒÔ·½±ãµÄÓÃ:List<String> Quer ......
¿ÉÒÔɸѡÊý¾Ý£¬µ«²»ÄÜÊDZê×¼µÄSQLÓï¾ä£º
Me.DsUserManager1.Tables(0).Select("id > 5 and id <20")
---------------------------------------------------------------
1.ɸѡ£º
dataset.tables("tabname").select("id=1")'Ï൱ÓÚSQLÖÐWHEREºóµÄÌõ¼þÄÚÈÝ
2.±£´æµ½ÄÄ£¿Õâµ¹ÊDz»Öª ......
Äãд¹ýÒ»ÌõsqlÓï¾äÀ´ÐÞ¸ÄÁ½¸ö±íµÄÊý¾ÝÂð£¿
UPDATE test.table1 t1,test.table2 t2 SET t1.aa='a',t1.bb='b',t2.cc='c',WHERE t1.u_id=t2.u_id AND t1.u_id='1' £»
table1µÄu_idºÍtable2µÄu_idÊÇÖ÷Íâ¼ü¹ØÏµ ......