求一个DBhelp类。好长时间不做项目了。

Question

求一个DBhelp类。好长时间不做项目了。要完整DBHelp类的代码。有的发下。。高分求。

Answer 1

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
namespace XDKJ
{
    public static class DBHelp
    {
        private static SqlConnection connection;
        /// <summary>
        /// 建立数据库连接
        /// </summary>
        public static SqlConnection Connection
        {
            get
            {
                string connectionString = ConfigurationManager.AppSettings["XDKJ"].ToString();
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                    connection.Open();
                }
                else if (connection.State == ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();
                }
                return connection;
            }
        }
        public static int ExecuteCommand(string safeSql)
        {
            int relust=0;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                relust = command.ExecuteNonQuery();
            }
            return relust;
        }
        public static int ExecuteCommand(string safeSql, params SqlParameter[] values)
        {
            int relust = 0;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                command.Parameters.AddRange(values);
                relust = command.ExecuteNonQuery();
            }
            return relust;
        }
        public static int ExecuteCommand(string safeSql,SqlTransaction st, params SqlParameter[] values)
        {
            int relust = 0;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                command.Transaction = st;
                command.Parameters.AddRange(values);
                relust = command.ExecuteNonQuery();
            }
            return relust;
        }
        public static SqlDataReader GetReader(string safeSql)
        {
            SqlDataReader relust;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                relust = command.ExecuteReader();
            }
            return relust;
        }
        public static SqlDataReader GetReader(string safeSql,params SqlParameter[] values)
        {
            SqlDataReader relus;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                command.Parameters.AddRange(values);
                relus = command.ExecuteReader();
            }
            return relus;
        }
        public static DataTable GetAdapter(string safeSql)
        {
            SqlDataAdapter da;
            DataSet ds;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                da = new SqlDataAdapter(command);
                ds = new DataSet();
                da.Fill(ds);
            }
            return ds.Tables[0];
        }
        public static DataTable GetAdapter(string safeSql, params SqlParameter[] values)
        {
            SqlDataAdapter da;
            DataSet ds;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                command.Parameters.AddRange(values);
                da = new SqlDataAdapter(command);
                ds = new DataSet();
                da.Fill(ds);
            }
            return ds.Tables[0];
        }
        public static object GetOneNote(string safeSql)
        {
            object relust;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                relust = command.ExecuteScalar();
            }
            return relust;
        }
        public static object GetOneNote(string safeSql, params SqlParameter[] values)
        {
            object relust;
            using(SqlCommand command = new SqlCommand(safeSql,Connection))
            {
                command.CommandTimeout = 0;
                command.Parameters.AddRange(values);
                relust=command.ExecuteScalar();
            }
            return relust;
        }
        public static object GetOneNote(string safeSql,SqlTransaction st, params SqlParameter[] values)
        {
            object relust;
            using (SqlCommand command = new SqlCommand(safeSql, Connection))
            {
                command.CommandTimeout = 0;
                command.Transaction = st;
                command.Parameters.AddRange(values);
                relust = command.ExecuteScalar();
            }
            return relust;
        }
    }
}

Answer 2

给你一个我自己用的，有SqlHelper和OracleHelper，用于SqlServer和Oracle的http://download.csdn.net/source/1556669

Answer 3

现在这年头用dbhelper太落后了。
都用linq做映射，强大有方便。

Answer 4

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;namespace DHOffice.SQLServerDAL
{
    /// <summary>
    /// Copyright (C) 
    /// 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)
        //<add key="ConnectionString" value="server=127.0.0.1;database=DATABASE;uid=sa;pwd=" />
        protected static string connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;        public static string ConnectionString
        {
            set { connectionString = value; }
            get { return connectionString; }        }
        public DbHelperSQL()
        {
        }        #region 公用方法        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)
                    {
                        connection.Close();
                        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 void ExecuteSqlTran(ArrayList SQLStringList)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand();
                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();
                }
                catch (System.Data.SqlClient.SqlException E)
                {
                    tx.Rollback();
                    throw new Exception(E.Message);
                }
            }
        }
        /// <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))
            {
                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);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }

Answer 5

[Quote=引用 4 楼 y82907966 的回复:]
接下
[Quote]        /// <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))
            {
                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);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }        /// <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)
                    {
                        connection.Close();
                        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(string strSQL)
        {
            SqlConnection connection = new SqlConnection(connectionString);
            SqlCommand cmd = new SqlCommand(strSQL, connection);
            try
            {
                connection.Open();
                SqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                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
                    {
                        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 void ExecuteSqlTran(Hashtable SQLStringList)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                conn.Open();
                using (SqlTransaction trans = conn.BeginTransaction())
                {
                    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();
                        }
                    }
                    catch
                    {
                        trans.Rollback();
                        throw;
                    }
                }
            }
        }

Answer 6

        /// <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
                    {
                        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(string SQLString, params SqlParameter[] cmdParms)
        {
            SqlConnection connection = new SqlConnection(connectionString);
            SqlCommand cmd = new SqlCommand();
            try
            {
                PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                SqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                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))
            {
                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)
        {
            if (conn.State != ConnectionState.Open)
                conn.Open();
            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="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>SqlDataReader</returns>
        public static SqlDataReader RunProcedure(string storedProcName, IDataParameter[] parameters)
        {
            SqlConnection connection = new SqlConnection(connectionString);            SqlDataReader returnReader;
            connection.Open();
            SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters);
            command.CommandType = CommandType.StoredProcedure;
            returnReader = command.ExecuteReader(CommandBehavior.CloseConnection);
            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);
                connection.Close();
                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></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;
                //Connection.Close();
                return result;
            }
        }        /// <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>SqlCommand 对象实例</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    }
}

Answer 7

看看petshop，操作数据库类很完整
http://topic.csdn.net/u/20090808/10/89f29f28-8b4d-4f16-8844-f367e3952f78.html
public abstract class SqlHelper
    {
        public static readonly string ConnectionStringKy = Param.GetConStr();
        private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());        protected SqlHelper()
        {
        }        public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters)
        {
            parmCache[cacheKey] = commandParameters;
        }        public static DataSet ExecuteDataSet(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteDataSet(ConnectionStringKy, cmdType, cmdText, commandParameters);
        }        public static DataSet ExecuteDataSet(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            SqlDataAdapter adapter = new SqlDataAdapter();
            adapter.SelectCommand = cmd;
            DataSet dataSet = new DataSet();
            adapter.Fill(dataSet);
            cmd.Parameters.Clear();
            return dataSet;
        }        public static DataSet ExecuteDataSet(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
                SqlDataAdapter adapter = new SqlDataAdapter();
                adapter.SelectCommand = cmd;
                DataSet dataSet = new DataSet();
                adapter.Fill(dataSet);
                cmd.Parameters.Clear();
                return dataSet;
            }
        }        public static int ExecuteNonQuery(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteNonQuery(ConnectionStringKy, cmdType, cmdText, commandParameters);
        }        public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            int num = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return num;
        }        public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
            int num = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return num;
        }        public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            cmd.CommandTimeout = 60;
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
                int num = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return num;
            }
        }        public static SqlDataReader ExecuteReader(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteReader(ConnectionStringKy, cmdType, cmdText, commandParameters);
        }        public static SqlDataReader ExecuteReader(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            SqlDataReader reader = cmd.ExecuteReader();
            cmd.Parameters.Clear();
            return reader;
        }        public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlDataReader reader2;
            SqlCommand cmd = new SqlCommand();
            SqlConnection conn = new SqlConnection(connectionString);
            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                reader2 = reader;
            }
            catch
            {
                conn.Close();
                throw;
            }
            return reader2;
        }        public static object ExecuteScalar(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteScalar(ConnectionStringKy, cmdType, cmdText, commandParameters);
        }        public static object ExecuteScalar(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            object obj2 = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return obj2;
        }        public static object ExecuteScalar(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
            object obj2 = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return obj2;
        }        public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
                object obj2 = cmd.ExecuteScalar();
                cmd.Parameters.Clear();
                return obj2;
            }
        }        public static DataTable ExecuteTable(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            return ExecuteTable(ConnectionStringKy, cmdType, cmdText, commandParameters);
        }        public static DataTable ExecuteTable(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            SqlDataAdapter adapter = new SqlDataAdapter();
            adapter.SelectCommand = cmd;
            DataSet dataSet = new DataSet();
            adapter.Fill(dataSet, "Result");
            cmd.Parameters.Clear();
            return dataSet.Tables["Result"];
        }     

Answer 8

   public static DataTable ExecuteTable(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
                SqlDataAdapter adapter = new SqlDataAdapter();
                adapter.SelectCommand = cmd;
                DataSet dataSet = new DataSet();
                adapter.Fill(dataSet, "Result");
                cmd.Parameters.Clear();
                if (dataSet.Tables.Count > 0)
                {
                    return dataSet.Tables["Result"];
                }
                return null;
            }
        }        public static SqlParameter[] GetCachedParameters(string cacheKey)
        {
            SqlParameter[] parameterArray = (SqlParameter[])parmCache[cacheKey];
            if (parameterArray == null)
            {
                return null;
            }
            SqlParameter[] parameterArray2 = new SqlParameter[parameterArray.Length];
            int index = 0;
            int length = parameterArray.Length;
            while (index < length)
            {
                parameterArray2[index] = (SqlParameter)((ICloneable)parameterArray[index]).Clone();
                index++;
            }
            return parameterArray2;
        }        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
        {
            if (conn.State != ConnectionState.Open)
            {
                conn.Open();
            }
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            cmd.CommandTimeout = 60;
            if (trans != null)
            {
                cmd.Transaction = trans;
            }
            cmd.CommandType = cmdType;
            if (cmdParms != null)
            {
                foreach (SqlParameter parameter in cmdParms)
                {
                    cmd.Parameters.Add(parameter);
                }
            }
        }
    }

Answer 9

偶也来一个.微软的WebCast视频中使用的类， 共四段。
前三段参考：http://topic.csdn.net/u/20090626/11/3564a7d4-e706-42b3-8cd2-1028ba137a31.html
中的 12 13 14 楼， 第四段内容为：//=====================================================GetDataTable()==============================================      #region 执行查询，并以DataTable返回结果集  GetDataTable(string sql)        /**//// <summary>
        /// 执行查询，并以DataTable返回结果集
        /// </summary>
        /// <param name="sql">SQL语句 </param>
        /// <param name="cmdtype">命令类型 </param>
        /// <param name="parameters">参数 </param>
        /// <returns>DataTable </returns>
        public DataTable GetDataTable(string sql)
        {
            DbParameter[] parameters = new DbParameter[0];
            DataTable dt = GetDataSet(sql, CommandType.Text, parameters).Tables[0];
            return dt;
        }
        /**//// <summary>
        /// 执行查询，并以DataTable返回结果集
        /// </summary>
        /// <param name="sql">SQL语句 </param>
        /// <param name="cmdtype">命令类型 </param>
        /// <param name="parameters">参数 </param>
        /// <returns>DataTable </returns>
        public DataTable GetDataTable(string sql, CommandType cmdtype)
        {
            DbParameter[] parameters = new DbParameter[0];
            DataTable dt = GetDataSet(sql, cmdtype, parameters).Tables[0];
            return dt;
        }
        /**//// <summary>
        /// 执行查询，并以DataTable返回结果集
        /// </summary>
        /// <param name="sql">SQL语句 </param>
        /// <param name="cmdtype">命令类型 </param>
        /// <param name="parameters">参数 </param>
        /// <returns>DataTable </returns>
        public DataTable GetDataTable(string sql, DbParameter[] parameters)
        {            DataTable dt = GetDataSet(sql, CommandType.Text, parameters).Tables[0];
            return dt;
        }        /**//// <summary>
        /// 执行查询，并以DataTable返回结果集
        /// </summary>
        /// <param name="sql">SQL语句 </param>
        /// <param name="cmdtype">命令类型 </param>
        /// <param name="parameters">参数 </param>
        /// <returns>DataTable </returns>
        public DataTable GetDataTable(string sql, CommandType cmdtype, DbParameter[] parameters)
        {
            DataTable dt = GetDataSet(sql, cmdtype, parameters).Tables[0];
            return dt;
        }        /**//// <summary>
        /// 执行查询,并以DataTable返回指定记录的结果集
        /// </summary>
        /// <param name="sql">SQL语句 </param>
        /// <param name="StartIndex">开始索引 </param>
        /// <param name="RecordCount">显示记录 </param>
        /// <returns>DataTable </returns>
        public DataTable GetDataTable(string sql, int StartIndex, int RecordCount)
        {
            return GetDataSet(sql, StartIndex, RecordCount).Tables[0];
        }        /**//// <summary>
        /// 执行查询,返回以空行填充的指定条数记录集
        /// </summary>
        /// <param name="sql">SQL语句 </param>
        /// <param name="SizeCount">显示记录条数 </param>
        /// <returns>DataTable </returns>
        public DataTable GetDataTable(string sql, int SizeCount)
        {
            DataTable dt = GetDataSet(sql).Tables[0];
            int b = SizeCount - dt.Rows.Count;
            if (dt.Rows.Count < SizeCount)
            {
                for (int i = 0; i < b; i++)
                {
                    DataRow dr = dt.NewRow();
                    dt.Rows.Add(dr);
                }
            }
            return dt;
        }        #endregion    }
} 

Answer 10

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Data.Common;
using System.Collections.Generic;
namespace Maticsoft.DBUtility
{
    /// <summary>
    /// 数据访问抽象基础类
    /// Copyright (C) 2004-2008 By LiTianPing 
    /// </summary>
    public abstract class DbHelperSQL
    {
        string pa = System.IO.Directory.GetCurrentDirectory();        //数据库连接字符串(web.config来配置)，可以动态更改connectionString支持多数据库.
        public static string connectionString = PubConstant.ConnectionString;     
        public DbHelperSQL()
        {            
        }        #region 公用方法
        /// <summary>
        /// 判断是否存在某表的某个字段
        /// </summary>
        /// <param name="tableName">表名称</param>
        /// <param name="columnName">列名称</param>
        /// <returns>是否存在</returns>
        public static bool ColumnExists(string tableName, string columnName)
        {
            string sql = "select count(1) from syscolumns where [id]=object_id('" + tableName + "') and [name]='" + columnName + "'";
            object res = GetSingle(sql);
            if (res == null)
            {
                return false;
            }
            return Convert.ToInt32(res) > 0;
        }
        public static int GetMaxID(string FieldName, string TableName)
        {
            string strsql = "select max(" + FieldName + ")+1 from " + TableName;
            object obj = DbHelperSQL.GetSingle(strsql);
            if (obj == null)
            {
                return 1;
            }
            else
            {
                return int.Parse(obj.ToString());
            }
        }
        public static bool Exists(string strSql)
        {
            object obj = DbHelperSQL.GetSingle(strSql);
            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;
            }
        }
        /// <summary>
        /// 表是否存在
        /// </summary>
        /// <param name="TableName"></param>
        /// <returns></returns>
        public static bool TabExists(string TableName)
        {
            string strsql = "select count(*) from sysobjects where id = object_id(N'[" + TableName + "]') and OBJECTPROPERTY(id, N'IsUserTable') = 1";
            //string strsql = "SELECT count(*) FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[" + TableName + "]') AND type in (N'U')";
            object obj = DbHelperSQL.GetSingle(strsql);
            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;
            }
        }
        public static bool Exists(string strSql, params SqlParameter[] cmdParms)
        {
            object obj = DbHelperSQL.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)
                    {
                        connection.Close();
                        throw  e;
                    }
                }
            }
        }

Answer 11

本人从事Java行业，也来献一献丑，望指正：using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data;
using System.Data.SqlClient;/// <summary>
/// 数据库基本操作类
/// </summary>
public class SqlHelper
{
    private SqlConnection con = null;    private SqlCommand cmd = null;    private SqlDataAdapter da = null;    private DataSet ds = null;    public static SqlHelper getInstance()
    {
        return new SqlHelper();
    }    // 建立与数据库的连接
    private void Connection()
    {
        string sqlCon = "Data Source=fs-erpserver;Initial Catalog=snErpForWeb;Persist Security Info=True;User ID=snerpuser;Password=snerp2008";
        con = new SqlConnection(sqlCon);
        con.Open();
    }    /// <summary>
    /// 执行对数据库增、删、改等操作
    /// </summary>
    /// <param name="procName">存储过程名</param>
    /// <param name="param">存储过程的参数</param>
    public void ExecuteProc(string procName, SqlParameter[] param)
    {
        try
        {
            this.Connection();
            cmd = new SqlCommand(procName, con);
            cmd.CommandType = CommandType.StoredProcedure;
            for (int i = 0, len = param.Length; i < len; i++)
            {
                cmd.Parameters.Add(param[i]);
            }
            cmd.ExecuteNonQuery();
        }
        catch
        {
        }
        finally
        {
            Close();
        }
    }    /// <summary>
    /// 执行对数据库的查询操作
    /// </summary>
    /// <param name="procName">存储过程名</param>
    /// <param name="param">存储过程的参数</param>
    /// <param name="tableName">表名</param>
    /// <returns>数据集</returns>
    public DataSet ExecuteQuery(string procName, SqlParameter[] param, string tableName)
    {
        try
        {
            this.Connection();
            da = new SqlDataAdapter();
            da.SelectCommand = new SqlCommand(procName, con);
            da.SelectCommand.CommandType = CommandType.StoredProcedure;
            for (int i = 0, len = param.Length; i < len; i++)
            {
                da.SelectCommand.Parameters.Add(param[i]);
            }
            ds = new DataSet();
            da.Fill(ds, tableName);
            return ds;
        }
        catch
        {
        }
        finally
        {
            Close();
        }
        return null;
    }    // 关闭与数据库的连接
    private void Close()
    {
        if (con != null && con.State != ConnectionState.Closed)
        {
            con.Close();
        }
    }}