Ò׽ؽØÍ¼Èí¼þ¡¢µ¥Îļþ¡¢Ãâ°²×°¡¢´¿ÂÌÉ«¡¢½ö160KB

Linq to SQL Like Operator(×ªÔØ)


As a response for customer's question, I decided to write about using Like Operator in Linq to SQL queries.
Starting from a simple query from Northwind Database;
var query = from c in ctx.Customers
            where c.City == "London"
            select c;
The query that will be sent to the database will be:
SELECT CustomerID, CompanyName, ...
from    dbo.Customers
WHERE  City = [London]
There are some ways to write a Linq query that reaults in using Like Operator in the SQL statement:
1. Using String.StartsWith or String.Endswith
Writing the following query:
var query = from c in ctx.Customers
            where c.City.StartsWith("Lo")
            select c;
will generate this SQL statement:
SELECT CustomerID, CompanyName, ...
from    dbo.Customers
WHERE  City LIKE [Lo%]
which is exactly what we wanted. Same goes with String.EndsWith.
But, what is we want to query the customer with city name like "L_n%"? (starts with a Capital 'L', than some character, than 'n' and than the rest of the name). Using the query
var query = from c in ctx.Customers
            where c.City.StartsWith("L") && c.City.Contains("n")
            select c;
generates the statement:
SELECT CustomerID, CompanyName, ...
from    dbo.Customers
WHERE  City LIKE [L%]
AND      City LIKE [%n%]
which is not exactly what we wanted, and a little more complicated as well.
2. Using SqlMethods.Like method
Digging into System.Data.Linq.SqlClient namespace, I found a little helper class called SqlMethods, which can be very usefull in such scenarios. SqlMethods


Ïà¹ØÎĵµ£º

Oracle 10g ÒªµãÕûÀí Ö® ÉÁ»Ø£¨½öÏÞÓÚSQL*Plus£©

ÉÁ»Ø
1 ÌØÕ÷
ÉÁ»ØÊý¾Ý¿âÖ»ÊÇÂß¼­Êý¾ÝÔâµ½ÆÆ»µÊ±µÄÊֶΡ£
ÉÁ»ØÊý¾Ý¿âÈÕÖ¾±ØÐëÔÚÊý¾Ý¿â»Ö¸´ÇøÖд´½¨¡£
ÉÁ»ØÈÕÖ¾²»ÐèÒª¹éµµ£¬²»ÄÜÓÃÓÚÎïÀí»Ö¸´¡£
Ö´ÐÐÉÁ»ØÊý¾Ý¿â²Ù×÷ʱ£¬±³¾°½ø³ÌRVWR¾ÍÆô¶¯ÁË¡£
 
2 ʹÓÃÉÁ»ØÊý¾Ý¿â
3ÖÖ¹¤¾ß£¬SQL*Plus£¬RMAN£¬OEM¡£
£¨1£©ÒªÇó
ΪÁËʹÓÃÉÁ»ØÊý¾Ý¿â£¬Êý¾Ý¿â±ØÐë´¦Óڹ鵵ÈÕ־ģʽ¡ ......

SQL ServerÈçºÎ½Ø¶Ï(Truncate)ºÍÊÕËõ(Shrink)ÊÂÎñÈÕÖ¾

µ±SQL Server½Ø¶ÏÊÂÎñÈÕ־ʱ£¬Ëü½ö½öÊÇÔÚÐéÄâÈÕÖ¾ÎļþÖÐ×ö¸ö±ê¼Ç£¬ÒԱ㲻ÔÙʹÓÃËü£¬È»ºó×¼±¸ÒÔÖØÓÃÐÎʽÀ´×ö±¸·Ý(¼ÙÈçÔËÔØÔÚÍêÕû»òÊÇÅúÁ¿ÈÕÖ¾»Ö¸´Ä£ÐÍ)¡£Ò²¾ÍÊÇ˵£¬ÔÚʹÓüòµ¥»Ö¸´Ä£ÐÍʱ£¬ÊÂÎñÈÕÖ¾°üÀ¨ÈçϵÄÈÕÖ¾¼Ç¼£º

µ±checkpoint·¢Éúʱ£¬ÐéÄâÈÕÖ¾Îļþ1¡¢2²»ÔÙ±»Ê¹Óã¬ÒòΪÊÂÎñ1¡¢2ÒѾ­±»Ìá½»ÁË£¬¶øÇÒÈÕÖ¾¼Ç¼Ҳ²»ÔÙÐ ......

SQL ServerÊý¾Ý¿â±¸·ÝºÍ»Ö¸´´ëÊ©

Ò»¡¢±¸·ÝÊý¾Ý¿â
1¡¢´ò¿ªSQLÆóÒµ¹ÜÀíÆ÷£¬ÔÚ¿ØÖÆÌ¨¸ùĿ¼ÖÐÒÀ´Îµã¿ªMicrosoft SQL Server
2¡¢SQL Server×é-->Ë«»÷´ò¿ªÄãµÄ·þÎñÆ÷-->Ë«»÷´ò¿ªÊý¾Ý¿âĿ¼
3¡¢Ñ¡ÔñÄãµÄÊý¾Ý¿âÃû³Æ£¨ÈçÂÛ̳Êý¾Ý¿âForum£©-->È»ºóµãÉÏÃæ²Ëµ¥ÖеŤ¾ß-->Ñ¡Ôñ±¸·ÝÊý¾Ý¿â
4¡¢±¸·ÝÑ¡ÏîÑ¡ÔñÍêÈ«±¸·Ý£¬Ä¿µÄÖеı¸·Ýµ½Èç¹ûÔ­À´Óз¾¶ºÍÃû³ ......

¡¾Ñ§Ï°É¢¼Ç7 SQLÓï¾äµÄ´¦Àí¡¿

SQLÓï¾äµÄ´¦Àí
ps£ºMSDNÕª
ÓÅ»¯ ÔÚ»ù´¡±íÉÏ£¨²»ÒýÓÃÊÓͼ»òÔ¶³Ì±í£©µÄ SELECT Óï¾ä:SELECT Óï¾äÊǷdzÌÐòÐÔµÄ,ÕâÒâζ×ÅÊý¾Ý¿â·þÎñÆ÷±ØÐë·ÖÎöÓï¾ä£¬ÒÔ¾ö¶¨ÌáÈ¡ËùÇëÇóÊý¾ÝµÄ×îÓÐЧ·½·¨
´¦ÀíÉÏÃæ²½ÖèµÄ×é¼þ³ÆÎª“²éѯÓÅ»¯Æ÷”£º
   ÊäÈ룺²éѯ¡¢Êý¾Ý¿â·½°¸£¨±íºÍË÷ÒýµÄ¶¨Ò壩ÒÔ¼°Êý¾Ý¿âͳ¼ÆÐÅÏ¢
& ......

SQL Server±¸·ÝÊÂÎñÈÕÖ¾½áβ(Tail)

ÊÂÎñÈÕÖ¾½áβ¾­³£Ìá½»Êý¾Ý¿âδ±¸·ÝµÄÊÂÎñÈÕÖ¾ÄÚÈÝ¡£»ù±¾ÉÏ£¬Ã¿Ò»´ÎÄãÖ´ÐÐÊÂÎñÈÕÖ¾±¸·Ýʱ£¬Äã¶¼ÔÚÖ´ÐÐÊÂÎñÈÕÖ¾½áβµÄ±¸·Ý¡£
ÄÇΪʲô»áÕâôÉè¼ÆÄØ£¿ÒòΪҲÐíÓÉÓÚ½éÖʵÄË𻵣¬µ±Êý¾Ý¿âÒѾ­²»ÔÙ¿ÉÓÃʱ£¬Âé·³¾ÍÀ´ÁË¡£Èç¹ûÏÂÒ»¸öÂß¼­²½ÖèÕýºÃ¾ÍÊÇÒª±¸·Ýµ±Ç°ÊÂÎñÈÕÖ¾µÄ»°£¬¿ÉÒÔÓ¦ÓÃÕâ¸ö±¸·ÝÀ´Ê¹Êý¾Ý¿â´¦Óڵȴý(Standby)״̬¡£ÄãÉ ......
© 2009 ej38.com All Rights Reserved. ¹ØÓÚE½¡ÍøÁªÏµÎÒÃÇ | Õ¾µãµØÍ¼ | ¸ÓICP±¸09004571ºÅ