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using System;
using System.Collections;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace DAL
{
public class DataControl
{
public static string connectionString = "server=" + SystemSet.getServerSet_ServerIP() + ";uid=" + SystemSet.getServerSet_ServerUser() + ";pwd=" + SystemSet.getServerSet_ServerPass() + ";database=" + SystemSet.getServerSet_ServerDataBase() + "";
/// <summary>
/// ³õʼ»¯ /// </summary>
public DataControl()
{
}
/// <summary>
/// ÎÞ²ÎÊý£¬²âÊÔÊý¾Ý¿âÁ¬½ÓÊÇ·ñÉèÖúÏÀí¡£ /// </summary>
/// <returns>ÊÇ·ñÁ¬½Ó³É¹¦</returns>
public static bool checkconn()
{
try
{
SqlConnection conn = new SqlConnection(connectionString);
conn.Open();
return true;
}
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PairWise subquery:
e.g.:
select * from wf_docsort where (ndocsortid,nmoduleinfoid) in (select ndocsortid, nmoduleinfoid from wf_docsort where instr(cname,'ÎÄ')>0)
the above sql is the same function as:
select * from wf_docsort where ndocsortid = (select ndocsortid from wf_docsort where ......
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1.cross join È«ÍâÁ¬½Ó(µÑ¿¨¶û³Ë»ý)
SELECT A.*, B.* from A FULL OUTER JOIN B ON A.ID = B.ID
2.inner join ÄÚÁ¬½Ó(Ôڵѿ¨¶û³Ë»ýµÄ½á¹û¼¯ÖÐÈ¥µô²»·ûºÏÁ¬½ÓÌõ¼þµÄÐÐ)
SELECT A.* from A INNER JOIN B ON A.ID=B.ID
3.left outer join ×óÍâÁ¬½Ó(ÔÚinner joinµÄ½á¹ ......
--> Title : SQL ServerϵͳÊÓͼ
--> Author : wufeng4552
--> Date : 2009-10-28
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Ŀ¼ÊÓͼ·µ»Ø SQL Server Êý¾Ý¿âÒýÇæʹÓõÄÐÅÏ¢¡£½¨ÒéÄúʹÓÃĿ¼ÊÓͼÕâÒ»×î³£ÓõÄĿ¼ԪÊý¾Ý½çÃ棬Ëü¿ÉΪÄúÌṩ×îÓÐЧµÄ·½·¨À´»ñÈ¡¡¢×ª»»²¢ÏÔʾ´ËÐÅÏ¢µÄ×Ô¶¨ÒåÐÎʽ¡£ËùÓÐÓû§¿ÉÓÃĿ¼Ԫ ......