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¡ ......

C#´ò°üSQLÊý¾Ý¿â²¿Êð°²×°


²Î¿¼¡¶ASP.NETÓëSQLÒ»Æð´ò°ü²¿Êð°²×°¡·
£¬ÕâÆªÎÄÕÂÊÇÕë¶ÔVB.NETÓëSQL Ò»Æð´ò°üµÄ,µ«ÊÇÎÒʹÓõÄÊÇC#,µ±È»Ö»ÒªÐÞ¸ÄÒ»ÏÂÖ÷Òª°²×°Àà¿â¾ÍÐÐÁË!C#µÄÀà¿â´úÂëÈçÏÂ:DBCustomAction.cs
using System;
using System.Collections;
using System.Data.SqlClient;
using System.ComponentModel;
using System.Configuration.Inst ......

SQL ServerÖд洢¹ý³ÌÓ뺯ÊýµÄÇø±ð

SQL ServerÓû§×Ô¶¨Ò庯ÊýºÍ´æ´¢¹ý³ÌÓÐÀàËÆµÄ¹¦ÄÜ£¬¶¼¿ÉÒÔ´´½¨À¦°óSQLÓï¾ä£¬´æ´¢ÔÚserverÖй©ÒÔºóʹÓá£ÕâÑùÄܹ»¼«´óµØÌá¸ß¹¤×÷ЧÂÊ£¬Í¨¹ýÒÔϵĸ÷ÖÖ×ö·¨¿ÉÒÔ¼õÉÙ±à³ÌËùÐèµÄʱ¼ä£º
¡¡¡¡ 1 ÖØ¸´Ê¹Óñà³Ì´úÂ룬¼õÉÙ±à³Ì¿ª·¢Ê±¼ä¡£
¡¡¡¡ 2 Òþ²ØSQLϸ½Ú£¬°ÑSQL·±ËöµÄ¹¤×÷Áô¸øÊý¾Ý¿â¿ª·¢ÈËÔ±£¬¶ø³ÌÐò¿ª·¢Ô±Ôò¼¯Öд¦Àí¸ß¼¶±à³Ì ......
© 2009 ej38.com All Rights Reserved. ¹ØÓÚE½¡ÍøÁªÏµÎÒÃÇ | Õ¾µãµØÍ¼ | ¸ÓICP±¸09004571ºÅ