SQL Server 2005 UNIQUE Ô¼Êø
SQL Server 2005£º
ALTER Table Content_Node
ADD CONSTRAINT uc_TREECODE UNIQUE (TreeCode)
ALTER TABLE Content_Node
DROP CONSTRAINT uc_TREECODE
Ô¼ÊøËùÔÚ×ֶ㤶ÈÉèΪ896£¬ÒòΪUNIQUEÔ¼ÊøµÄ×î´ó¼ü³¤¶ÈΪ 900 ×Ö½Ú£¬¶øUNIQUEÔ¼ÊøÄ¬ÈÏÕ¼ÓÐ4×Ö½Ú¡£
²Î¿¼£ºhttp://www.w3school.com.cn/sql/sql_unique.asp
Ïà¹ØÎĵµ£º
DATEDIFF
·µ»Ø¿çÁ½¸öÖ¸¶¨ÈÕÆÚµÄÈÕÆÚºÍʱ¼ä±ß½çÊý¡£
Ò»¡¢ Óï·¨
DATEDIFF ( datepart , startdate , enddate )
¶þ¡¢²ÎÊý
datepar ......
Linq to SQL uses a DataContext to manage it's access to the database as well as tracking changes made to entities retrieved from the database. Linq to SQL has a persistent approach to managing its 'connection' to the database via this data context and it basically assumes that you use a single Dat ......
1.Oracleɾ³ýÖØ¸´¼Ç¼.
ɾ³ý±íÖжàÓàµÄÖØ¸´¼Ç¼£¬Öظ´¼Ç¼ÊǸù¾Ýµ¥¸ö×ֶΣ¨peopleId£©À´Åжϣ¬Ö»ÁôÓÐrowid×îСµÄ¼Ç¼.
delete from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
and rowid not i ......
ORACLE SQLÐÔÄÜÓÅ»¯ÏµÁÐ
1. ·ÃÎÊTableµÄ·½Ê½
ORACLE ²ÉÓÃÁ½ÖÖ·ÃÎʱíÖмǼµÄ·½Ê½:
a. È«±íɨÃè
È«±íɨÃè¾ÍÊÇ˳ÐòµØ·ÃÎʱíÖÐÿÌõ¼Ç¼. ORACLE²ÉÓÃÒ»´Î¶ÁÈë¶à¸öÊý¾Ý¿é(database block)µÄ·½Ê½ÓÅ»¯È«±íɨÃè.
b. ͨ¹ýROWID·ÃÎʱí
Äã¿ÉÒÔ²ÉÓûùÓÚROWIDµÄ·ÃÎÊ·½Ê½Çé¿ö,Ìá¸ß·ÃÎʱíµÄЧÂÊ, , ROWID°üº¬Á˱íÖмǼµ ......
insert into Country123 ([Country_Id], [Region_ID], [Country_EN_Name], [Country], [Country_ALL_ID], [Country_Order_Id]) select [Country_Id], [Region_ID], [Country_EN_Name], [Country], [Country_ALL_ID], [Country_Order_Id] from openrowset( 'Microsoft.Jet.OLEDB.4.0', 'EXCEL 5.0;HDR=YES;IMEX=1; DATABASE= ......