SqlHelper封装

     首先，SqlHelper要定义为抽象类型的。原因：抽象类型的不能实例化。

    其次，抽象的SqlHelper中的函数类型为Static静态的。原因：非静态的抽象类中的函数不引用不能使用。

 

1，框架

    public abstract class SqlHelper
    {
        //数据库连接字符串
        public static string connectionString = ConnectionString; //读取配置文件中的连接字符串
        public SqlHelper()
        {            
        }
     }

 

2，不带参数的操作

2.1查询

/// <summary>
        /// 执行查询语句，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close )
        /// </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 e;
            }   

        }
        /// <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;
            }
        }

 

2.2查询带事务

 /// <summary>
        /// 执行多条SQL语句，实现数据库事务。
        /// </summary>
        /// <param name="SQLStringList">多条SQL语句的集合</param>        
        public static int ExecuteSqlTran(List<String> SQLStringList)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;

                SqlTransaction tx = conn.BeginTransaction();//实例化事务，并开始执行事务
                cmd.Transaction = tx; 
                try
                {
                    int count = 0;
                    for (int n = 0; n < SQLStringList.Count; n++)
                    {
                        string strsql = SQLStringList[n];
                        if (strsql.Trim().Length > 1)
                        {
                            cmd.CommandText = strsql;
                            count += cmd.ExecuteNonQuery();
                        }
                    }
                    tx.Commit();//提交事务
                    return count;
                }
                catch
                {
                    tx.Rollback();//事务回滚
                    return 0;
                }
            }
        }

 

 3，带参数的查询

3.1存储过程为参数

/// <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 object ExecuteSqlGet(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();
                    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 e;
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }

 

3.2查询

/// <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;
                }
            }
        }

 

准备command，将参数附加上去。

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 parameter in cmdParms)
                {
                    if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
                        (parameter.Value == null))
                    {
                        parameter.Value = DBNull.Value;
                    }
                    cmd.Parameters.Add(parameter);
                }
            }
        }

 

3.3非查询

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 e;
                    }
                }
            }
        }

 

3.4事务 （参数为哈希函数）

 /// <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;
                    }
                }
            }
        }

 

/// <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 int ExecuteSqlTran(System.Collections.Generic.List<CommandInfo> cmdList)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                conn.Open();
                using (SqlTransaction trans = conn.BeginTransaction())
                {
                    SqlCommand cmd = new SqlCommand();
                    try
                    { int count = 0;
                        //循环
                        foreach (CommandInfo myDE in cmdList)
                        {
                            string cmdText = myDE.CommandText;
                            SqlParameter[] cmdParms = (SqlParameter[])myDE.Parameters;
                            PrepareCommand(cmd, conn, trans, cmdText, cmdParms);
                           
                            if (myDE.EffentNextType == EffentNextType.WhenHaveContine || myDE.EffentNextType == EffentNextType.WhenNoHaveContine)
                            {
                                if (myDE.CommandText.ToLower().IndexOf("count(") == -1)
                                {
                                    trans.Rollback();
                                    return 0;
                                }

                                object obj = cmd.ExecuteScalar();
                                bool isHave = false;
                                if (obj == null && obj == DBNull.Value)
                                {
                                    isHave = false;
                                }
                                isHave = Convert.ToInt32(obj) > 0;

                                if (myDE.EffentNextType == EffentNextType.WhenHaveContine && !isHave)
                                {
                                    trans.Rollback();
                                    return 0;
                                }
                                if (myDE.EffentNextType == EffentNextType.WhenNoHaveContine && isHave)
                                {
                                    trans.Rollback();
                                    return 0;
                                }
                                continue;
                            }
                            int val = cmd.ExecuteNonQuery();
                            count += val;
                            if (myDE.EffentNextType == EffentNextType.ExcuteEffectRows && val == 0)
                            {
                                trans.Rollback();
                                return 0;
                            }
                            cmd.Parameters.Clear();
                        }
                        trans.Commit();
                        return count;
                    }
                    catch
                    {
                        trans.Rollback();
                        throw;
                    }
                }
            }
        }

 

 

 

 

 

附：

namespace DBUtility
{
    public enum EffentNextType
    {
        /// <summary>
        /// 对其他语句无任何影响 
        /// </summary>
        None,
        /// <summary>
        /// 当前语句必须为"select count(1) from .."格式，如果存在则继续执行，不存在回滚事务
        /// </summary>
        WhenHaveContine,
        /// <summary>
        /// 当前语句必须为"select count(1) from .."格式，如果不存在则继续执行，存在回滚事务
        /// </summary>
        WhenNoHaveContine,
        /// <summary>
        /// 当前语句影响到的行数必须大于0，否则回滚事务
        /// </summary>
        ExcuteEffectRows,
        /// <summary>
        /// 引发事件-当前语句必须为"select count(1) from .."格式，如果不存在则继续执行，存在回滚事务
        /// </summary>
        SolicitationEvent
    }   
    public class CommandInfo
    {
        public object ShareObject = null;
        public object OriginalData = null;
        event EventHandler _solicitationEvent;
        public event EventHandler SolicitationEvent
        {
            add
            {
                _solicitationEvent += value;
            }
            remove
            {
                _solicitationEvent -= value;
            }
        }
        public void OnSolicitationEvent()
        {
            if (_solicitationEvent != null)
            {
                _solicitationEvent(this,new EventArgs());
            }
        }
        public string CommandText;
        public System.Data.Common.DbParameter[] Parameters;
        public EffentNextType EffentNextType = EffentNextType.None;
        public CommandInfo()
        {

        }
        public CommandInfo(string sqlText, SqlParameter[] para)
        {
            this.CommandText = sqlText;
            this.Parameters = para;
        }
        public CommandInfo(string sqlText, SqlParameter[] para, EffentNextType type)
        {
            this.CommandText = sqlText;
            this.Parameters = para;
            this.EffentNextType = type;
        }
    }
}