关于C#连接SQLServer

1、配置文件App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>
  <appSettings>
    <add key="ConnectionString" value="server=127.0.0.1;database=test;uid=sa;pwd=;pooling=true;min pool size=1;max pool size=30;connect timeout=15;" />
  </appSettings>
</configuration>

2、数据库操作类DbHelperSQL.cs

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace app
{
  /// <summary>
  /// Copyright (C) 2014
  /// 数据访问基础类(基于SQLServer)
  /// 用户可以修改满足自己项目的需要。
  /// </summary>
  public abstract class DbHelperSQL
  {
    //数据库连接字符串(web.config来配置)
        protected static string connectionString = ConfigurationManager.AppSettings["ConnectionString"];
    public DbHelperSQL()
    {

    }

    #region 公用方法

        public static int GetCount(string TableName, string Condition)
        {
            string strsql = "select count(1) from " + TableName + " where " + Condition;
            object obj = GetSingle(strsql);
            if (obj == null)
            {
                return 0;
            }
            else
            {
                return int.Parse(obj.ToString());
            }
        }

        public static string GetNameByCode(string TableName, string Name, string Code, string CodeValue)
        {
            string strsql = "select " + Name + " from " + TableName + " where " + Code + " = '" + CodeValue + "'";
            object obj = GetSingle(strsql);
            if (obj == null)
            {
                return "";
            }
            else
            {
                return obj.ToString();
            }
        }

        public static string GetNameByCondition(string TableName, string Name, string Condition)
        {
            string strsql = "select " + Name + " from " + TableName + " " + Condition;
            object obj = GetSingle(strsql);
            if (obj == null)
            {
                return "";
            }
            else
            {
                return obj.ToString();
            }
        }

    public static int GetMaxID(string FieldName, string TableName)
    {
      string strsql = "select max(" + FieldName + ")+1 from " + TableName;
      object obj = GetSingle(strsql);
      if (obj == null)
      {
        return 1;
      }
      else
      {
        return int.Parse(obj.ToString());
      }
    }

    public static bool Exists(string strSql, params SqlParameter[] cmdParms)
    {
      object obj = GetSingle(strSql, cmdParms);
      int cmdresult;
      if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
      {
        cmdresult = 0;
      }
      else
      {
        cmdresult = int.Parse(obj.ToString());
      }
      if (cmdresult == 0)
      {
        return false;
      }
      else
      {
        return true;
      }
    }
    #endregion

    #region  执行简单SQL语句

    /// <summary>
    /// 执行SQL语句，返回影响的记录数
    /// </summary>
    /// <param name="SQLString">SQL语句</param>
    /// <returns>影响的记录数</returns>
    public static int ExecuteSql(string SQLString)
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {				
        using (SqlCommand cmd = new SqlCommand(SQLString,connection))
        {
                    try
                    {
                        connection.Open();
                        int rows = cmd.ExecuteNonQuery();
                        return rows;
                    }
                    catch (System.Data.SqlClient.SqlException E)
                    {
                        throw new Exception(E.Message);
                    }
        }				
      }
    }
    
    /// <summary>
    /// 执行多条SQL语句，实现数据库事务。
    /// </summary>
    /// <param name="SQLStringList">多条SQL语句</param>		
    public static int ExecuteSqlTran(ArrayList SQLStringList)
    {
      using (SqlConnection conn = new SqlConnection(connectionString))
      {
                using (SqlCommand cmd = new SqlCommand())
                {
                    conn.Open();
                    cmd.Connection = conn;
                    SqlTransaction tx = conn.BeginTransaction();
                    cmd.Transaction = tx;
                    try
                    {
                        for (int n = 0; n < SQLStringList.Count; n++)
                        {
                            string strsql = SQLStringList[n].ToString();
                            if (strsql.Trim().Length > 1)
                            {
                                cmd.CommandText = strsql;
                                cmd.ExecuteNonQuery();
                            }
                        }
                        tx.Commit();

                        return 0;
                    }
                    catch (System.Data.SqlClient.SqlException E)
                    {
                        tx.Rollback();
                        E.ToString();
                        //throw new Exception(E.Message);
                        return -1;
                    }
                }
      }
    }

    /// <summary>
    /// 执行带一个存储过程参数的的SQL语句。
    /// </summary>
    /// <param name="SQLString">SQL语句</param>
    /// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加</param>
    /// <returns>影响的记录数</returns>
    public static int ExecuteSql(string SQLString,string content)
    {				
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
                using (SqlCommand cmd = new SqlCommand(SQLString, connection))
                {
                    System.Data.SqlClient.SqlParameter myParameter = new System.Data.SqlClient.SqlParameter("@content", SqlDbType.NText);
                    myParameter.Value = content;
                    cmd.Parameters.Add(myParameter);
                    try
                    {
                        connection.Open();
                        int rows = cmd.ExecuteNonQuery();
                        return rows;
                    }
                    catch (System.Data.SqlClient.SqlException E)
                    {
                        throw new Exception(E.Message);
                    }
                }
      }
    }	
  
    /// <summary>
    /// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例)
    /// </summary>
    /// <param name="strSQL">SQL语句</param>
    /// <param name="fs">图像字节,数据库的字段类型为image的情况</param>
    /// <returns>影响的记录数</returns>
    public static int ExecuteSqlInsertImg(string strSQL,byte[] fs)
    {		
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
                using (SqlCommand cmd = new SqlCommand(strSQL, connection))
                {
                    System.Data.SqlClient.SqlParameter myParameter = new System.Data.SqlClient.SqlParameter("@fs", SqlDbType.Image);
                    myParameter.Value = fs;
                    cmd.Parameters.Add(myParameter);
                    try
                    {
                        connection.Open();
                        int rows = cmd.ExecuteNonQuery();
                        return rows;
                    }
                    catch (System.Data.SqlClient.SqlException E)
                    {
                        throw new Exception(E.Message);
                    }
                }
      }
    }
    
    /// <summary>
    /// 执行一条计算查询结果语句，返回查询结果（object）。
    /// </summary>
    /// <param name="SQLString">计算查询结果语句</param>
    /// <returns>查询结果（object）</returns>
    public static object GetSingle(string SQLString)
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
        using(SqlCommand cmd = new SqlCommand(SQLString,connection))
        {
                    try
                    {
                        connection.Open();
                        object obj = cmd.ExecuteScalar();
                        if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                        {
                            return null;
                        }
                        else
                        {
                            return obj;
                        }
                    }
                    catch (System.Data.SqlClient.SqlException e)
                    {
                        throw new Exception(e.Message);
                    }
        }
      }
    }

    /// <summary>
    /// 执行查询语句，返回SqlDataReader
    /// </summary>
        /// <param name="connection">连接数据源</param>
    /// <param name="strSQL">查询语句</param>
    /// <returns>SqlDataReader</returns>
        public static SqlDataReader ExecuteReader(SqlConnection connection, string strSQL)
    {
            connection = new SqlConnection(connectionString);
            using (SqlCommand cmd = new SqlCommand(strSQL, connection))
            {
                try
                {
                    connection.Open();
                    SqlDataReader myReader = cmd.ExecuteReader();
                    return myReader;
                }
                catch (System.Data.SqlClient.SqlException e)
                {
                    throw new Exception(e.Message);
                }
            }
    }	
  
    /// <summary>
    /// 执行查询语句，返回DataSet
    /// </summary>
    /// <param name="SQLString">查询语句</param>
    /// <returns>DataSet</returns>
    public static DataSet Query(string SQLString)
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
        DataSet ds = new DataSet();
        try
        {
          connection.Open();
          SqlDataAdapter command = new SqlDataAdapter(SQLString,connection);				
          command.Fill(ds,"ds");
        }
        catch(System.Data.SqlClient.SqlException ex)
        {				
          throw new Exception(ex.Message);
        }			
        return ds;
      }			
    }

    #endregion

    #region 执行带参数的SQL语句

    /// <summary>
    /// 执行SQL语句，返回影响的记录数
    /// </summary>
    /// <param name="SQLString">SQL语句</param>
    /// <returns>影响的记录数</returns>
    public static int ExecuteSql(string SQLString,params  SqlParameter[] cmdParms)
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {				
        using (SqlCommand cmd = new SqlCommand())
        {
          try
          {
                        connection.Open();
            PrepareCommand(cmd, connection, null,SQLString, cmdParms);
            int rows=cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return rows;
          }
          catch(System.Data.SqlClient.SqlException E)
          {				
            throw new Exception(E.Message);
          }
        }				
      }
    }

      
    /// <summary>
    /// 执行多条SQL语句，实现数据库事务。
    /// </summary>
    /// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的SqlParameter[]）</param>
    public static bool ExecuteSqlTran(Hashtable SQLStringList)
    {			
      using (SqlConnection conn = new SqlConnection(connectionString))
      {   
                conn.Open();
        using (SqlTransaction trans = conn.BeginTransaction()) 
        {
                    using (SqlCommand cmd = new SqlCommand())
                    {
                        try
                        {
                            
                            //循环
                            foreach (DictionaryEntry myDE in SQLStringList)
                            {
                                string cmdText = myDE.Key.ToString();
                                SqlParameter[] cmdParms = (SqlParameter[])myDE.Value;
                                PrepareCommand(cmd, conn, trans, cmdText, cmdParms);
                                int val = cmd.ExecuteNonQuery();
                                cmd.Parameters.Clear();
                            }

                            trans.Commit();
                            return true;
                        }
                        catch
                        {
                            trans.Rollback();
                            return false;
                        }
                    }
        }				
      }
    }
  
        
    /// <summary>
    /// 执行一条计算查询结果语句，返回查询结果（object）。
    /// </summary>
    /// <param name="SQLString">计算查询结果语句</param>
    /// <returns>查询结果（object）</returns>
    public static object GetSingle(string SQLString,params SqlParameter[] cmdParms)
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
        using (SqlCommand cmd = new SqlCommand())
        {
          try
          {
                        connection.Open();

            PrepareCommand(cmd, connection, null,SQLString, cmdParms);
            object obj = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            if((Object.Equals(obj,null))||(Object.Equals(obj,System.DBNull.Value)))
            {					
              return null;
            }
            else
            {
              return obj;
            }				
          }
          catch(System.Data.SqlClient.SqlException e)
          {				
            throw new Exception(e.Message);
          }					
        }
      }
    }
    
    /// <summary>
    /// 执行查询语句，返回SqlDataReader
    /// </summary>
    /// <param name="strSQL">查询语句</param>
    /// <returns>SqlDataReader</returns>
        public static SqlDataReader ExecuteReader(SqlConnection connection, string SQLString, params SqlParameter[] cmdParms)
    {
            connection = new SqlConnection(connectionString);
            using (SqlCommand cmd = new SqlCommand())
            {
                try
                {
                    connection.Open();
                    PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                    SqlDataReader myReader = cmd.ExecuteReader();
                    cmd.Parameters.Clear();
                    return myReader;
                }
                catch (System.Data.SqlClient.SqlException e)
                {
                    throw new Exception(e.Message);
                }
            }
    }		
    
    /// <summary>
    /// 执行查询语句，返回DataSet
    /// </summary>
    /// <param name="SQLString">查询语句</param>
    /// <returns>DataSet</returns>
    public static DataSet Query(string SQLString,params SqlParameter[] cmdParms)
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
                using (SqlCommand cmd = new SqlCommand())
                {
                    PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                    using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                    {
                        DataSet ds = new DataSet();
                        try
                        {
                            da.Fill(ds, "ds");
                            cmd.Parameters.Clear();
                        }
                        catch (System.Data.SqlClient.SqlException ex)
                        {
                            throw new Exception(ex.Message);
                        }
                        return ds;
                    }
                }
      }			
    }


    private static void PrepareCommand(SqlCommand cmd,SqlConnection conn,SqlTransaction trans, string cmdText, SqlParameter[] cmdParms) 
    {
      cmd.Connection = conn;
      cmd.CommandText = cmdText;
      if (trans != null)
        cmd.Transaction = trans;
      cmd.CommandType = CommandType.Text;//cmdType;
      if (cmdParms != null) 
      {
        foreach (SqlParameter parm in cmdParms)
          cmd.Parameters.Add(parm);
      }
    }

    #endregion

    #region 存储过程操作

    /// <summary>
    /// 执行存储过程
    /// </summary>
        /// <param name="connection">数据连接源</param>
    /// <param name="storedProcName">存储过程名</param>
    /// <param name="parameters">存储过程参数</param>
    /// <returns>SqlDataReader</returns>
        public static SqlDataReader RunProcedure(SqlConnection connection, string storedProcName, IDataParameter[] parameters)
    {
            connection = new SqlConnection(connectionString);
            connection.Open();
            using (SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters))
            {
                 command.CommandType = CommandType.StoredProcedure;
                 SqlDataReader returnReader = command.ExecuteReader();
                 return returnReader;
            }
    }
    
    
    /// <summary>
    /// 执行存储过程
    /// </summary>
    /// <param name="storedProcName">存储过程名</param>
    /// <param name="parameters">存储过程参数</param>
    /// <param name="tableName">DataSet结果中的表名</param>
    /// <returns>DataSet</returns>
    public static DataSet RunProcedure(string storedProcName, IDataParameter[] parameters, string tableName )
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
        DataSet dataSet = new DataSet();
        connection.Open();
        SqlDataAdapter sqlDA = new SqlDataAdapter();
        sqlDA.SelectCommand = BuildQueryCommand(connection, storedProcName, parameters );
        sqlDA.Fill( dataSet, tableName );
        return dataSet;
      }
    }

        ///// <summary>
        ///// 执行存储过程-返回参数
        ///// </summary>
        ///// <param name="storedProcName">存储过程名</param>
        ///// <param name="parameters">存储过程参数</param>
        ///// <param name="tableName">DataSet结果中的表名</param>
        ///// <returns>DataSet</returns>
        public static DataSet RunProcedure(string storedProcName, IDataParameter[] parameters, string tableName, ref string TotalRecordCount, ref string PageCount)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                DataSet dataSet = new DataSet();
                connection.Open();
                SqlDataAdapter sqlDA = new SqlDataAdapter();
                sqlDA.SelectCommand = BuildQueryCommand(connection, storedProcName, parameters);
                sqlDA.Fill(dataSet, tableName);
                //总记录数
                TotalRecordCount = sqlDA.SelectCommand.Parameters["@TotalRecordCount"].Value.ToString();
                //总页数
                PageCount = sqlDA.SelectCommand.Parameters["@PageCount"].Value.ToString(); 
                return dataSet;
            }
        }

    /// <summary>
    /// 构建 SqlCommand 对象(用来返回一个结果集，而不是一个整数值)
    /// </summary>
    /// <param name="connection">数据库连接</param>
    /// <param name="storedProcName">存储过程名</param>
    /// <param name="parameters">存储过程参数</param>
    /// <returns>SqlCommand</returns>
    private static SqlCommand BuildQueryCommand(SqlConnection connection,string storedProcName, IDataParameter[] parameters)
    {			
      SqlCommand command = new SqlCommand(storedProcName, connection );
      command.CommandType = CommandType.StoredProcedure;
      foreach (SqlParameter parameter in parameters)
      {
        command.Parameters.Add( parameter );
      }
      return command;			
    }
    
    /// <summary>
    /// 执行存储过程，返回影响的行数		
    /// </summary>
    /// <param name="storedProcName">存储过程名</param>
    /// <param name="parameters">存储过程参数</param>
    /// <param name="rowsAffected">影响的行数</param>
    /// <returns>结果值</returns>
    public static int RunProcedure(string storedProcName, IDataParameter[] parameters, out int rowsAffected )
    {
      using (SqlConnection connection = new SqlConnection(connectionString))
      {
        int result;
        connection.Open();
        SqlCommand command = BuildIntCommand(connection,storedProcName, parameters );
        rowsAffected = command.ExecuteNonQuery();
        result = (int)command.Parameters["ReturnValue"].Value;
        return result;
      }
    }


        /// <summary>
        /// 执行存储过程,返回影响的行数
        /// </summary>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <param name="getParam">要还么的参数的值</param>
        /// <returns>结果值</returns>
        public static string RunProc(string storedProcName, IDataParameter[] parameters,string getParam)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                connection.Open();
                SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters);
                command.ExecuteNonQuery();
                return (string)command.Parameters[getParam].Value;
            }
        }

    /// <summary>
    /// 创建 SqlCommand 对象实例(用来返回一个整数值)	
    /// </summary>
    /// <param name="storedProcName">存储过程名</param>
    /// <param name="parameters">存储过程参数</param>
        /// <returns>存储过程参数</returns>
    private static SqlCommand BuildIntCommand(SqlConnection connection,string storedProcName, IDataParameter[] parameters)
    {
      SqlCommand command = BuildQueryCommand(connection,storedProcName, parameters );
      command.Parameters.Add(new SqlParameter ( "ReturnValue",
        SqlDbType.Int,4,ParameterDirection.ReturnValue,
        false,0,0,string.Empty,DataRowVersion.Default,null ));
      return command;
    }
    #endregion	

  }
}

3、测试代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;

namespace app
{
    class Program
    {
        static void Main(string[] args)
        {
            // 更新
            string strSql = "update app_users set user_name = 'jzhjzh' where user_code = '9001'";
            DbHelperSQL.ExecuteSql(strSql);

            // 查询
            strSql = "select user_code, user_name from app_users";
            DataSet ds = DbHelperSQL.Query(strSql.ToString());
            DataTable dt = ds.Tables[0];
            DataRow[] drs = dt.Select("");

            foreach (DataRow r in drs)
            {
                Console.WriteLine("行输出：" + r["user_code"].ToString() + "|" + r["user_name"].ToString());
            }

            // 统计
            int GetCount = DbHelperSQL.GetCount("app_users", "user_code = '9001'");
            // 输出
            Console.WriteLine("统计：" + GetCount);
            // 设置一个输入，避免控制台界面关闭
            Console.ReadLine();
        }
    }
}