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]
AS
SELECT     dbo.result.id AS resultid, dbo.users.id, dbo.users.name, dbo.users.phone, dbo.awards.Name AS awardname
FROM         dbo.awards INNER JOIN
                      dbo.result ON dbo.awards.id = dbo.result.awardsid INNER JOIN
                      dbo.users ON dbo.result.usersid = dbo.users.id

CREATE 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id
AS 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id
DECLARE @maxid int --最小id
DECLARE @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id
SET @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 BEGIN
SELECT @randnum = ROUND(((@maxid - @minid -1) * RAND() + @minid), 0)
SET @exist =
  (SELECT count(*)
   FROM users
   WHERE id=@randnum) IF @exist = 1 BEGIN
INSERT 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

=====================================================================================

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：

==========================================================================================

知识点：

SQL - 生成指定范围内的随机数

DECLARE @Result INT DECLARE @Upper INT DECLARE @Lower INT
SET @Lower = 1
SET @Upper = 10
SELECT @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 int
SET @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