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();