每天进步一点点_抽奖程序

抽奖程序：

思路整理，无非就是点一个按钮，然后一个图片旋转一会就出来个结果就行了，可这个程序的要求不是这样的，是需要从数据库中随机抽取用户，根据数据库中指定的等级和人数，一键全部抽出来结果就行了。同时需要存储到数据库。还需要一个导出的功能。

不能遗漏的是，如果通过随机数根据id来抽取的话，需要考虑id不连续的问题，如果全部取出id也不现实。尽量少的去读写数据库。

数据库：

CREATE TABLE [dbo].[users](    [id] [int] IDENTITY(1,1) NOT NULL,    [name] [nvarchar](50) NOT NULL,    [phone] [nvarchar](50) NULL, CONSTRAINT [PK_table1] PRIMARY KEY CLUSTERED (    [id] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]CREATE TABLE [dbo].[result]( [id] [int] IDENTITY(1,1) NOT NULL, [usersid] [int] NOT NULL, [awardsid] [int] NOT NULL, CONSTRAINT [PK_result] PRIMARY KEY CLUSTERED ( [id] ASC)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]) ON [PRIMARY]CREATE TABLE [dbo].[awards]( [id] [int] IDENTITY(1,1) NOT NULL, [Name] [nvarchar](50) NOT NULL, [Number] [int] NOT NULL, CONSTRAINT [PK_awards] PRIMARY KEY CLUSTERED ( [id] ASC)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]) ON [PRIMARY]CREATE VIEW [dbo].[view1]ASSELECT     dbo.result.id AS resultid, dbo.users.id, dbo.users.name, dbo.users.phone, dbo.awards.Name AS awardnameFROM         dbo.awards INNER JOIN                      dbo.result ON dbo.awards.id = dbo.result.awardsid INNER JOIN                      dbo.users ON dbo.result.usersid = dbo.users.idCREATE PROCEDURE [dbo].[getranddata] --这个地方的参数是后台调用传的参数，两个变量之间需要“,”号分开@count int, --剩余奖项大小@awards int --奖项的idAS BEGIN --这个地方定义的参数是存储过程内部用到的DECLARE @minid int --最大idDECLARE @maxid int --最小idDECLARE @randnum int --随机数临时变量DECLARE @exist int --查询结果SET @minid =  (SELECT top 1 id   FROM users   ORDER BY id ASC) --查询最小idSET @maxid =  (SELECT top 1 id   FROM users   ORDER BY id DESC) --查询最大id--set @count = 100--set @awards = 1--嵌套语句begin开始，end结束while @count>0 BEGINSELECT @randnum = ROUND(((@maxid - @minid -1) * RAND() + @minid), 0)SET @exist =  (SELECT count(*)   FROM users   WHERE id=@randnum) IF @exist = 1 BEGININSERT INTO result(usersid,awardsid)VALUES(@randnum,       @awards)SET @count = @count - 1 END END END

其中三张表，一个视图，一个存储过程。

标题链接：http://www.cnblogs.com/zxlovenet/p/3713536.html

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后台代码：

protected void Button1_Click(object sender, EventArgs e){    SqlConnection sqlcon = new SqlConnection("server=.;database=test;uid=sa;pwd=123");    sqlcon.Open();    SqlDataAdapter sqlsda = new SqlDataAdapter("select * from awards", sqlcon);    ds = new DataSet();    sqlsda.Fill(ds);    DataTable dt = ds.Tables[0].Copy();    ds.Clear();    int count = dt.Rows.Count;    for (int i = 0; i < count; i++)    {        SqlCommand sqlcmd = new SqlCommand("getranddata", sqlcon);        SqlParameter pcount = new SqlParameter("@count", Convert.ToInt32(dt.Rows[i]["Number"]));        SqlParameter pawards = new SqlParameter("@awards", Convert.ToInt32(dt.Rows[i]["id"]));        sqlcmd.Parameters.Add(pcount);        sqlcmd.Parameters.Add(pawards);        sqlcmd.CommandType = CommandType.StoredProcedure;        sqlcmd.ExecuteNonQuery();        sqlsda = new SqlDataAdapter("select top " + Convert.ToInt32(dt.Rows[i]["Number"]) + " * from view1 order by resultid desc", sqlcon);        sqlsda.Fill(ds, "t" + i.ToString());        switch (i)        {        case 0:            GridView1.DataSource = ds.Tables["t" + i.ToString()].Copy().DefaultView;            GridView1.DataBind();            break;        case 1:            GridView2.DataSource = ds.Tables["t" + i.ToString()].Copy().DefaultView;            GridView2.DataBind();            break;        case 2:            GridView3.DataSource = ds.Tables["t" + i.ToString()].Copy().DefaultView;            GridView3.DataBind();            break;        default:            break;        }    }    sqlcon.Close();}

奖项设置：

抽奖结果：

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知识点：

SQL - 生成指定范围内的随机数

DECLARE @Result INT DECLARE @Upper INT DECLARE @Lower INTSET @Lower = 1SET @Upper = 10SELECT @Result = ROUND(((@Upper - @Lower -1) * RAND() + @Lower), 0)SELECT @Result

ROUND()函数：返回按指定位数进行四舍五入的数值。

RAND()函数：生成随机数。

SQL循环语句嵌套

DECLARE @i intSET @i=1 while @i<8 BEGIN IF @i<5 print space(4-@i)+REPLICATE('*',2*@i-1) ELSE print space(@i-4)+REPLICATE('*',15-2*@i)SET @i=@i + 1 END