近期一直在研究数据库，刚好有个项目要做抽奖程序，恩，拿来练练手吧。
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。
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 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