item.Name=dataReader.GetString(dataReader.GetOrdinal ("proName"));

www.programfan.com

用于操作左边数据库的代码

放在Main()方法下面

static void Main()

{

  string dataDir=AppDomain.CurrentDomain.BaseDirectory;

  if(dataDir.EndsWith(@"\bin\Debug\")

    ||dataDir.EndsWith(@"\bin\Release\"))

   {

      dataDir=System.IO.Directory.GetParent(dataDir).Parent.Parent.FullName;

      AppDomain.CurentDomain.SetData("DataDirectory",dataDir);

   }

将连接数据库字符串写到配置文件（新建项－配置文件）

<?xml version="1.0" encoding="utf-8"?>

<configuration>

  <connectionStrings>

    <add name="ConnStr" connetionString="Data Source=**;DataBase=**;pwd=***;uid=***">

  </connectionStrings>

</configuration>

//引用  添加引用

system.configuration;

/*************************

类中ToString 方法是调用基类的ToString(), 在类中重载ToString方法。

public override string ToString()

{

  return name;

}

combox  DisplayMember 属性 设置

using(SqlConnection conn=new SqlConnection(string strConn)

{

   conn.Open();

   using (SqlCommand cmd=conn.CreateCommand())

{

  cmd.CommandText="select * from city where proID=@proID";

  cmd.Parameters.Add=(new SqlParameter("proID",proID));

  using (SqlDataReader dataReader=cmd.ExecuteReader())

  {

    string cityName=dataReader.GetString(dataReader.GetOrdinal("cityName"));

    cmbCity.items.Add("cityName");

}

using(SqlConnection conn=new SqlConnection(string strConn)

{

   conn.Open();

   using (SqlCommand cmd=conn.CreateCommand())

{

  cmd.CommandText="select * from city where proID=@proID";

  cmd.Parameters.Add=(new SqlParameter("proID",proID));

  using (SqlDataReader dataReader=cmd.ExecuteReader())

  {

         while(dataReader.Read())

          {

            ProvinceItem item=new ProvinceItem();

            item.ID=dataReader.GetInt32(dataReader.GetOrdinal              ("proID"));

            item.Name=dataReader.GetString(dataReader.GetOrdinal           ("proName"));

           //添加到COMBOX下拉列表

            cmbPro.Items.Add(item);

           }

}

// dataset 中更新数据到数据库0

SqlCommandBuilder builder=new SqlCommandBuilder(adapter);

adapter.Update(dataset);

Data Source=(LocalDB)\v12.0;AttachDbFilename="E:\Visual Studio 2013\Projects\ADO.DB\WindowsFormsApplication1\Database12.mdf";Integrated Security=True

// 创建数据库 删除数据库表  删除数据

Create Table T_yuangong(id int not null, name nvarchar(10),age int null)

drop table T_yuangong

delete from T_yuangong where Age<18

SQL : ddl(数据定义语言）Create Table\ Drop Table  dml（数据操作语言）insert into 、 select* from Table where..... 、delete、update

//条件查询

select * from T_Employee Where FName like '_ry‘

select * from T_Employee Where FName like '%n%‘

select * from T_Employee Where FName is(not) null

select * from T_Employee Where FName in(Tim,Tom)

select * from T_Employee Where FName between 20 and 50

select * from T_Employee Where FAge>=20 and FAge<50

//分组查询 (聚合函数是不能放到Where 子句中的）

select FAge,Count(*) from T_Employee group by FAge

select FAge,Count(*) from T_Employee group by FAge having count(*)>2

// 查询语句的函数

ceiling 舍到最大 floor 舍到最小  round 四舍五入  ABS（）绝对值

LTRIM,RTRIM ,LTRIM(RTRIM()),DATEADD,DATEDIFF

类型转换

cast  convert

//添加 列

select FNumber,

sum(

  case

  when FAmount>0 than FAmount

  else 0

end

)as 收入

sum（

   case

   when FAmount<0 than ABS(FAmount)

   else 0

end

 )as 支出

from T_Amount

select Name,

sum(

 case Score

 when N'胜' than 1

 else 0

 end

)as 胜

sum(

 case Score

 when N'负' than 1

 else 0

 end

)as 负

from T_Score

group by Name

//强数据类型

批量操作之前 先将adapter打开,然后再关闭，这样可以提升效率

adapter.Connection.Open();

……………………………………

adapter.Connection.Close();