关于C# Ado.NET连接数据库操作基本实例模板

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data;

using System.Data.SqlClient;

namespace DB

{

//DBHelper实例模板

class DBHelper

{

//连接数据库字符串

private const string sqlStr = @"";

//返回第一行 第一列

public object SelecOne(string sql)

{

object obj = null;

SqlConnection conn = new SqlConnection(sqlStr);

try

{

//打开数据库连接

conn.Open();

SqlCommand cmd = new SqlCommand(sql,conn);

obj= cmd.ExecuteScalar();

}

catch (Exception ex)

{

Console.WriteLine(ex.Message);

}

finally

{

//关闭数据库连接

conn.Close();

}

return obj;

}

//执行update

public int Update(string sql)

{

int obj = -1;

SqlConnection conn = new SqlConnection(sqlStr);

try

{

//打开数据库连接

conn.Open();

SqlCommand cmd = new SqlCommand(sql, conn);

obj=cmd.ExecuteNonQuery();

}

catch (Exception ex)

{

Console.WriteLine(ex.Message);

}

finally

{

//关闭数据库连接

conn.Close();

}

return obj;

}

//执行读取多行 多列dataReader

public SqlDataReader SelectAll(string sql)

{

SqlDataReader dr = null;

SqlConnection conn = new SqlConnection(sqlStr);

try

{

conn.Open();

SqlCommand cmd = new SqlCommand(sql,conn);

dr=cmd.ExecuteReader(CommandBehavior.CloseConnection);

}

catch (Exception ex)

{

Console.WriteLine(ex.Message);

}

return dr;

}

}

}