引言

在项目需求中需要用到动态批量的删除数据库中的表，我们都知道在数据库中的数据是需要历史记录的所以我们这所谓的删除其实只是给它重命名然后打上时间戳，这样就可以标志着这个数据表在数据库中已经没有用了，但是其中的数据还是有用的，下面和大家分享这几天在项目中学习到的东西！！底层封装好的SQLhelper类，代码如下：

<span style="font-size:18px;">using System;
using System.Collections;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Transactions;
namespace ITOO.Library.Core.Common
{
    /// <summary>
    /// 数据库助手类
    /// </summary>
    public class SQLHelper
    {
        private SqlCommand cmd = null;
        private SqlConnection conn = null;
        private SqlDataReader sdr = null;
        /// <summary>
        /// 
        /// </summary>
        /// <param name="strDatabaseName"></param>
        /// <param name="IsGetNewConnection"></param>
        public SQLHelper(string strDatabaseName, bool IsGetNewConnection = false)
        {
            if (IsGetNewConnection == false)
            {
                conn = ConnectionFactory.GetCurrentConn(strDatabaseName);
            }
            else
            {
                conn = ConnectionFactory.GetNewConn(strDatabaseName);
            }
        }
        /// <summary>
        /// 无参构造函数
        /// </summary>
        public SQLHelper()
        {
        }
        private SqlConnection GetConnection(string strDatabaseName)
        {
            string strConnValue = ConfigHelper.ReadAppSetting(strDatabaseName);
            return new SqlConnection(strConnValue);
        }
        /// <summary>
        /// 获得数据库连接
        /// </summary>
        /// <returns></returns>
        private SqlConnection GetConnection()
        {
            if (conn.State == ConnectionState.Closed)
            {
                conn.Open();
            }
            return conn;
        }
        /// <summary>
        /// 关闭连接
        /// </summary>
        /// <param name="conn">数据库连接</param>
        public static void Close(SqlConnection conn)
        {
            if (conn != null)
            {
                try
                {
                    conn.Close();
                }
                catch (SqlException e)
                {
                    throw e;
                }
            }
        }
        /// <summary>
        /// 执行带参数的增删改命令
        /// </summary>
        /// <param name="cmmText"></param>
        /// <param name="para"></param>
        /// <param name="cmmType"></param>
        /// <returns></returns>
        public int ExecuteNonQuery(string cmmText, SqlParameter[] para, CommandType cmmType)
        {
            cmd = new SqlCommand(cmmText, GetConnection());
            cmd.CommandType = cmmType;
            try
            {
                cmd.Parameters.AddRange(para);
                return cmd.ExecuteNonQuery();
            }
            catch (SqlException e)
            {
                throw e;
            }
        }
        /// <summary>
        /// 执行不带参数的增删改命令
        /// </summary>
        /// <param name="cmmText"></param>
        /// <param name="cmmType"></param>
        /// <returns></returns>
        public int ExecuteNonQuery(string cmmText, CommandType cmmType)
        {
            cmd = new SqlCommand(cmmText, GetConnection());
            cmd.CommandType = cmmType;
            try
            {
                return cmd.ExecuteNonQuery();
            }
            catch (SqlException e)
            {
                throw e;
            }
        }
        /// <summary>
        /// 执行带参数的查询命令
        /// </summary>
        /// <param name="cmmText"></param>
        /// <param name="para"></param>
        /// <param name="cmmType"></param>
        /// <returns></returns>
        public DataTable ExecuteQuery(string cmmText, SqlParameter[] para, CommandType cmmType)
        {
            DataTable dt = new DataTable();
            cmd = new SqlCommand(cmmText, GetConnection());
            cmd.CommandType = cmmType;
            cmd.Parameters.AddRange(para);
            try
            {
                using (sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
                {
                    dt.Load(sdr);
                    return dt;
                }
            }
            catch (SqlException e)
            {
                throw e;
            }
        }
        /// <summary>
        /// 执行不带参数的查询命令
        /// </summary>
        /// <param name="cmmText"></param>
        /// <param name="cmmType"></param>
        /// <returns></returns>
        public DataTable ExecuteQuery(string cmmText, CommandType cmmType)
        {
            DataTable dt = new DataTable();
            cmd = new SqlCommand(cmmText, GetConnection());
            cmd.CommandType = cmmType;
            using (sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
            {
                dt.Load(sdr);
            }
            return dt;
        }
        /// <summary>
        /// 执行创建表的方法
        /// 先读取文件，以GO为段落，把每一个GO的段落当做一条SQL命令，在通过事务一起执行。
        /// </summary>
        /// <param name="varSqlList">传入执行的sql脚本</param>
        public void ExecuteCommand(ArrayList varSqlList)
        {
            SqlTransaction varTrans = GetConnection().BeginTransaction();
            cmd = new SqlCommand();
            cmd.Connection = GetConnection();
            cmd.Transaction = varTrans;
            try
            {
                foreach (string varcommandText in varSqlList)
                {
                    cmd.CommandText = varcommandText;
                    cmd.ExecuteNonQuery();
                }
                varTrans.Commit();
            }
            catch (Exception ex)
            {
                varTrans.Rollback();
                throw ex;
            }
        }
        #region 批量导入DataTable
        /// <summary>
        /// 批量导入DataTable
        /// </summary>
        /// <param name="strDatabaseName">配置文件key</param>
        /// <param name="dt">datatable名称</param>
        /// <param name="tableName">表名称</param>
        /// <param name="dtColum">所有列（dt.columns)</param>
        /// <returns>返回true，or false</returns>
        public Boolean InsertTable(string strDatabaseName, DataTable dt, string tableName, DataColumnCollection dtColum)
        {
            using (TransactionScope scope1 = new TransactionScope(TransactionScopeOption.Required))
            {
                using (SqlBulkCopy sqlBC = new SqlBulkCopy(
                           GetConnection(strDatabaseName).ConnectionString, SqlBulkCopyOptions.KeepIdentity))
                {
                    sqlBC.BatchSize = 1000;
                    sqlBC.DestinationTableName = tableName;
                    // Write from the source to the destination.
                    // This should fail with a duplicate key error.
                    for (int i = 0; i < dtColum.Count; i++)
                    {
                        sqlBC.ColumnMappings.Add(dtColum[i].ColumnName.ToString(), dtColum[i].ColumnName.ToString());
                    }
                    try
                    {
                        //批量写入
                        sqlBC.WriteToServer(dt);
                        scope1.Complete();
                        return true;
                    }
                    catch
                    {
                        throw new Exception("导入数据失败！");
                    }
                }
            }
        }
        #endregion 批量导入DataTable
    }</span>

删除数据表的方法

<span style="font-size:18px;">  /// <summary>
        /// 批量假删除数据表（重命名，打上时间戳）
        /// </summary>
        /// <param name="db">指定的数据库</param>
        /// <param name="listDt">要删除的数据库表集合</param>
        /// <param name="connKey">数据库连接串</param>
        /// <returns>执行是否成功，true表示成功，false表示失败</returns>
        public bool FalseDropTable(string db, List<string> listDt, string connKey)
        {
            SQLHelper helper = null;
            try
            {
                 helper = new SQLHelper("ITOOExamEntities");
            }
            catch (Exception e)
            {
                throw e;
            }
            string connToMaster = ConfigurationManager.ConnectionStrings[connKey].ToString();
            //判断数据库是否存在
            if (IsDBExist(db, connKey) == false)
            {
                throw new Exception("数据库不存在！");
            }
            string timeStamp = DateTime.Now.ToString();            // 2008-9-4 20:02:10
            for (int i = 0; i < listDt.Count(); i++)
            {
                //如果数据库表存在，则抛出错误
                if (IsTableExist(db, listDt[i], connKey) == false)
                {
                    //如果数据库表已经删除，则跳过该表
                    continue;
                }
                else//数据表存在，则进行删除数据表
                {
                    //其后判断数据表是否存在，然后创建数据表
                    //string createTableStr = "use " + db + " drop table " + listDt[i] + " ";
                    string createTableStr = "use " + db + " exec sp_rename '" + listDt[i] + "','" + listDt[i] + "_" + timeStamp + "'";
                    helper.ExecuteNonQuery(createTableStr, CommandType.Text);
                }
            }
            return true;
        }</span>

判断指定的数据库是否存在

<span style="font-size:18px;">/// <summary>
        /// 判断数据库是否存在
        /// </summary>
        /// <param name="db">数据库的名称</param>
        /// <param name="connKey">数据库的连接Key</param>
        /// <returns>true:表示数据库已经存在；false，表示数据库不存在</returns>
        public Boolean IsDBExist(string db, string connKey)
        {
            SQLHelper helper = new SQLHelper("ITOOExamEntities");
            string connToMaster = ConfigurationManager.ConnectionStrings[connKey].ToString();
            string createDbStr = " select * from master.dbo.sysdatabases where name " + "= '" + db + "'";
            DataTable dt = helper.ExecuteQuery(createDbStr, CommandType.Text);
            if (dt.Rows.Count == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }</span>

判断数据库中的指定的表是否存在

<span style="font-size:18px;">/// <summary>
        /// 判断数据库表是否存在
        /// </summary>
        /// <param name="db">数据库</param>
        /// <param name="tb">数据表名</param>
        /// <param name="connKey">连接数据库的key</param>
        /// <returns>true:表示数据表已经存在；false，表示数据表不存在</returns>
        public Boolean IsTableExist(string db, string tb, string connKey)
        {
            SQLHelper helper = new SQLHelper("ITOOExamEntities");
            string connToMaster = ConfigurationManager.ConnectionStrings[connKey].ToString();
            string createDbStr = "use " + db + " select 1 from  sysobjects where  id = object_id('" + tb + "') and type = 'U'";
            //在指定的数据库中  查找 该表是否存在
            DataTable dt = helper.ExecuteQuery(createDbStr, CommandType.Text);
            if (dt.Rows.Count == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }</span>

以上是小编在刚接手的项目中学习到的一些对于自己来说比较新的东西，在这分享给大家，希望能给大家带来帮助！！

动态批量删除SQL数据库中的表

引言

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