Asp.net DataHelper类

适合初学者的操作数据库类：

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Linq;
using System.Web;
using System.Data.SqlClient;
using System.Configuration;


namespace Web_TEST.Common
{
    public class SqlDbHelper
    {
        private string connectionString;
        /// <summary>
        /// 设置数据库连接字符串
        /// </summary>
        public string ConnectionString
        {
            set { connectionString = value; }
        }
        /// <summary>
        /// 构造函数
        /// </summary>
        public SqlDbHelper()
            : this(ConfigurationManager.ConnectionStrings["TESTConnectionString"].ConnectionString)
        {

        }
        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="connectionString">数据库连接字符串</param>
        public SqlDbHelper(string connectionString)
        {
            this.connectionString = connectionString;
        }
        /// <summary>
        /// 执行一个查询，并返回结果集
        /// </summary>
        /// <param name="sql">要执行的查询SQL文本命令</param>
        /// <returns>返回查询结果集</returns>
        public DataTable ExecuteDataTable(string sql)
        {
            return ExecuteDataTable(sql, CommandType.Text, null);
        }
        /// <summary>
        /// 执行一个查询,并返回查询结果
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <returns>返回查询结果集</returns>
        public DataTable ExecuteDataTable(string sql, CommandType commandType)
        {
            return ExecuteDataTable(sql, commandType, null);
        }
        /// <summary>
        /// 执行一个查询,并返回查询结果
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <param name="parameters">Transact-SQL 语句或存储过程的参数数组</param>
        /// <returns></returns>
        public DataTable ExecuteDataTable(string sql, CommandType commandType, SqlParameter[] parameters)
        {
            DataTable data = new DataTable();//实例化DataTable，用于装载查询结果集71
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand command = new SqlCommand(sql, connection))
                {
                    command.CommandType = commandType;//设置command的CommandType为指定的CommandType
                    //如果同时传入了参数，则添加这些参数
                    if (parameters != null)
                    {
                        foreach (SqlParameter parameter in parameters)
                        {
                            command.Parameters.Add(parameter);
                        }
                    }
                    //通过包含查询SQL的SqlCommand实例来实例化SqlDataAdapter
                    SqlDataAdapter adapter = new SqlDataAdapter(command);
                    adapter.Fill(data);//填充DataTable
                }
            }
            return data;
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sql">要执行的查询SQL文本命令</param>
        /// <returns></returns>
        public SqlDataReader ExecuteReader(string sql)
        {
            return ExecuteReader(sql, CommandType.Text, null);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <returns></returns>
        public SqlDataReader ExecuteReader(string sql, CommandType commandType)
        {
            return ExecuteReader(sql, commandType, null);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <param name="parameters">Transact-SQL 语句或存储过程的参数数组</param>
        /// <returns></returns>
        public SqlDataReader ExecuteReader(string sql, CommandType commandType, SqlParameter[] parameters)
        {
            SqlConnection connection = new SqlConnection(connectionString);
            SqlCommand command = new SqlCommand(sql, connection);
            //如果同时传入了参数，则添加这些参数
            if (parameters != null)
            {
                foreach (SqlParameter parameter in parameters)
                {
                    command.Parameters.Add(parameter);
                }
            }
            connection.Open();
            //CommandBehavior.CloseConnection参数指示关闭Reader对象时关闭与其关联的Connection对象
            return command.ExecuteReader(CommandBehavior.CloseConnection);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sql">要执行的查询SQL文本命令</param>
        /// <returns></returns>
        public Object ExecuteScalar(string sql)
        {
            return ExecuteScalar(sql, CommandType.Text, null);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <returns></returns>
        public Object ExecuteScalar(string sql, CommandType commandType)
        {
            return ExecuteScalar(sql, commandType, null);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <param name="parameters">Transact-SQL 语句或存储过程的参数数组</param>
        /// <returns></returns>
        public Object ExecuteScalar(string sql, CommandType commandType, SqlParameter[] parameters)
        {
            object result = null;
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand command = new SqlCommand(sql, connection))
                {
                    command.CommandType = commandType;//设置command的CommandType为指定的CommandType
                    //如果同时传入了参数，则添加这些参数
                    if (parameters != null)
                    {
                        foreach (SqlParameter parameter in parameters)
                        {
                            command.Parameters.Add(parameter);
                        }
                    }
                    connection.Open();//打开数据库连接
                    result = command.ExecuteScalar();
                }
            }
            return result;//返回查询结果的第一行第一列，忽略其它行和列
        }
        /// <summary>
        /// 对数据库执行增删改操作
        /// </summary>
        /// <param name="sql">要执行的查询SQL文本命令</param>
        /// <returns></returns>
        public int ExecuteNonQuery(string sql)
        {
            return ExecuteNonQuery(sql, CommandType.Text, null);
        }
        /// <summary>
        /// 对数据库执行增删改操作
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <returns></returns>
        public int ExecuteNonQuery(string sql, CommandType commandType)
        {
            return ExecuteNonQuery(sql, commandType, null);
        }
        /// <summary>
        /// 对数据库执行增删改操作
        /// </summary>
        /// <param name="sql">要执行的SQL语句</param>
        /// <param name="commandType">要执行的查询语句的类型，如存储过程或者SQL文本命令</param>
        /// <param name="parameters">Transact-SQL 语句或存储过程的参数数组</param>
        /// <returns></returns>
        public int ExecuteNonQuery(string sql, CommandType commandType, SqlParameter[] parameters)
        {
            int count = 0;
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand command = new SqlCommand(sql, connection))
                {
                    command.CommandType = commandType;//设置command的CommandType为指定的CommandType
                    //如果同时传入了参数，则添加这些参数
                    if (parameters != null)
                    {
                        foreach (SqlParameter parameter in parameters)
                        {
                            command.Parameters.Add(parameter);
                        }
                    }
                    connection.Open();//打开数据库连接
                    count = command.ExecuteNonQuery();
                    
                }
            }
            return count;//返回执行增删改操作之后，数据库中受影响的行数
        }
        /// <summary>
        /// 返回当前连接的数据库中所有由用户创建的数据库
        /// </summary>
        /// <returns></returns>
        public DataTable GetTables()
        {
            DataTable data = null;
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                connection.Open();//打开数据库连接
                data = connection.GetSchema("Tables");
            }
            return data;
        }
        /// <summary>
        /// 执行SQL事务
        /// </summary>
        /// <param name="sqls"></param>
        public void ExecuteBatchBySqls(List<string> sqls)
        {
            using (SqlConnection conn = new SqlConnection(this.connectionString))
            {
                SqlTransaction ot = null;
                using (SqlCommand cmd = new SqlCommand())
                {
                    try
                    {
                        conn.Open();
                        cmd.Connection = conn;
                        //开始事务
                        ot = conn.BeginTransaction();
                        cmd.Transaction = ot;
                        foreach (string sql in sqls)
                        {
                            if (sql.Trim().Length > 1)
                            {
                                cmd.CommandText = sql;
                                cmd.ExecuteNonQuery();
                            }
                        }
                        //提交事务
                        ot.Commit();
                    }
                    catch (Exception ex)
                    {
                        //事务回滚
                        ot.Rollback();
                        ex.Message.ToString();
                        //LogManager.WriteLog(ex.ToString());
                    }
                }
            }
        }
    }
}