博客

隐藏 Firefox 书签工具栏菜单中的“在标签页中打开书签组”

Tue, 13 Dec 2011 15:12:12 GMT

其实这个东西挺烦的，不小心点错了会开好多窗口，所以我决定把他隐藏了，要隐藏他就必须要用 Firefox 的 userChrome.css 文件了。

开始 -> 运行 -> 输入 %AppData%\Mozilla\Firefox\Profiles，然后进入里面类似 xxxxxxx.default 的目录，再进入 chrome 目录，把文件 userChrome-example.css 改名为 userChrome.css。

然后修改 userChrome.css 文件，增加下面的 CSS 语句：

menupopup[placespopup="true"] > menuseparator:nth-last-child(-n+2), 
menupopup[placespopup="true"] > menuseparator:nth-last-child(-n+2) + menuitem 
{ 
   display: none !important; 
}

MySQL 获取所有分类和每个分类的前几条记录

Tue, 13 Dec 2011 15:02:48 GMT

比如有文章表 Article(Id,Category,InsertDate)

现在要用SQL找出每种类型中时间最新的前N个数据组成的集合

SELECT A1.*  
FROM Article AS A1  
     INNER JOIN (SELECT A.Category,A.InsertDate 
                 FROM Article AS A  
                      LEFT JOIN Article AS B  
                        ON A.Category = B.Category  
                           AND A.InsertDate <= B.InsertDate  
                 GROUP BY A.Category,A.InsertDate 
                 HAVING COUNT(B.InsertDate) <= @N 
    ) AS B1  
    ON A1.Category = B1.Category  
       AND A1.InsertDate = B1.InsertDate 
ORDER BY A1.Category,A1.InsertDate DESC

@N 就是要取多少条

身份证号码验证函数

Tue, 13 Dec 2011 15:01:51 GMT

private bool CheckCardNumber(string number) 
{ 
    int[] iW = new int[] { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2, 1 }; 
    int iSum = 0; 
    for (int i = 0; i < 17; i++) 
    { 
        int iVal = 0; 
        int.TryParse(number[i].ToString(), out iVal); 
 
        iSum += iVal * iW[i]; 
    } 
 
    int iCheck = iSum % 11; 
 
    string check = string.Empty; 
 
    switch (iCheck) 
    { 
        case 0: check = "1"; break; 
        case 1: check = "0"; break; 
        case 2: check = "x"; break; 
        case 3: check = "9"; break; 
        case 4: check = "8"; break; 
        case 5: check = "7"; break; 
        case 6: check = "6"; break; 
        case 7: check = "5"; break; 
        case 8: check = "4"; break; 
        case 9: check = "3"; break; 
        case 10: check = "2"; break; 
    } 
 
    string valid = number[17].ToString().ToLower(); 
 
    return valid == check; 
}

SQL Server 2005 以上版本使用 CTE 分割字符串

Tue, 13 Dec 2011 14:59:54 GMT

ALTER FUNCTION [dbo].[UF_SpliteIntToTable] 
( 
    @String VARCHAR(8000) 
) 
RETURNS @Table TABLE (Id INT) 
AS 
BEGIN 
    DECLARE @SpliteChar AS CHAR(1) = ','; 
         
    WITH TempTable AS 
    ( 
        SELECT CAST(SUBSTRING(@String,1,CHARINDEX(@SpliteChar,@String,1) - 1) AS INT) AS item, 
        SUBSTRING(@String,CHARINDEX(@SpliteChar,@String,1) + 1, LEN(@String)) + @SpliteChar AS list 
 
        UNION ALL 
 
        SELECT CAST(SUBSTRING(list,1,CHARINDEX(@SpliteChar,list,1) - 1) AS INT) AS item, 
        SUBSTRING(list,CHARINDEX(@SpliteChar,list,1) + 1, LEN(list)) AS list 
        FROM TempTable 
        WHERE LEN(TempTable.list) > 0 
    ) 
 
    INSERT INTO @Table SELECT item FROM TempTable WHERE item > 0 
         
    RETURN 
END

SQL Server 中删除重复记录

Tue, 13 Dec 2011 14:54:58 GMT

最常用的 T-SQL 语句：

DELETE FROM [dbo].[myTable] WHERE 主键 NOT IN 
    (SELECT MAX(主键) From [dbo].[myTable] GROUP BY 列1, 列2, 列3)

SQL Server 2005 及以上版本，用 CTE：

WITH tmpOrderdTable 
AS 
( 
  SELECT  
    GroupID = ROW_NUMBER() OVER (PARTITION BY 列1, 列2, 列3 ORDER BY 主键) 
  FROM 
    [dbo].[myTable] 
) 
 
DELETE FROM tmpOrderdTable WHERE GroupID > 1

为了提高效率可以先开启单人存取模式，删除完再恢复多人存取模式：

# 开启单人存取模式  
USE [master]  
ALTER DATABASE [myDB] SET SINGLE_USER WITH ROLLBACK IMMEDIATE  
      
# 开启多人存取模式  
USE [master]  
ALTER DATABASE [myDB] SET MULTI_USER WITH ROLLBACK IMMEDIATE