关于MySql的DBHelper类以及数据分页
前端：
<%@ Register Assembly="AspNetPager" Namespace="Wuqi.Webdiyer" TagPrefix="webdiyer" %>
<webdiyer:AspNetPager ID="AspNetPager1" FirstPageText="首页" LastPageText="尾页" NextPageText="下一页" PrevPageText="上一页" runat="server" CssClass="pages" PagingButtonSpacing="0" CurrentPageButtonClass="cpb" PageSize="10" OnPageChanged="AspNetPager1_PageChanged">
</webdiyer:AspNetPager>
后台方法：
protected void BindGrid()
{
StringBuilder strWhere = new StringBuilder();
BLL.base_servicecount countBll = new BLL.base_servicecount();
strWhere.AppendFormat(" UserID='{0}' ", LoginUserModel.ID);
if (!string.IsNullOrEmpty(txtInput.Value.Trim()))
{
strWhere.AppendFormat(" AND (ProName like '%{0}%' or Brand like '%{0}%') ", txtInput.Value.Trim());
}
AspNetPager1.RecordCount = countBll.GetRecordCount(strWhere.ToString());
int itemStart = (AspNetPager1.CurrentPageIndex - ) * AspNetPager1.PageSize;
gridProduct.DataSource = countBll.GetMvListByPage_MySql(strWhere.ToString(), "", itemStart, AspNetPager1.PageSize);
gridProduct.DataBind();
}
protected void AspNetPager1_PageChanged(object sender, EventArgs e)
{
BindGrid();
}
DAL方法：
/// <summary>
/// 分页
/// </summary>
public DataTable GetMvListByPage_MySql(string strWhere, string orderBy, int startIndex, int PageCount)
{
StringBuilder strSql = new StringBuilder();
strSql.Append("SELECT * FROM mv_service_product ");
if (!string.IsNullOrEmpty(strWhere.Trim()))
{
strSql.Append(" WHERE " + strWhere);
}
if (!string.IsNullOrEmpty(orderBy.Trim()))
{
strSql.Append(" order by " + orderBy + " ");
}
else
{
strSql.Append(" order by Count desc ");
}
strSql.AppendFormat(" LIMIT {0},{1} ", startIndex, PageCount);
return DbHelperMySQL.Query(strSql.ToString()).Tables[] != null ? DbHelperMySQL.Query(strSql.ToString()).Tables[] : null;
}
DBHelperMySql类：
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using MySql.Data.MySqlClient;
using System.Configuration;
using System.Data.Common;
using System.Collections.Generic;
namespace ZHUAO.DBUtility
{
/// <summary>
/// 数据访问抽象基础类
/// Copyright (C) Maticsoft
/// </summary>
public abstract class DbHelperMySQL
{
//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 DbHelperMySQL()
{
} #region 公用方法
/// <summary>
/// 得到最大值
/// </summary>
/// <param name="FieldName"></param>
/// <param name="TableName"></param>
/// <returns></returns>
public static int GetMaxID(string FieldName, string TableName)
{
string strsql = "select max(" + FieldName + ")+1 from " + TableName;
object obj = GetSingle(strsql);
if (obj == null)
{
return ;
}
else
{
return int.Parse(obj.ToString());
}
}
/// <summary>
/// 是否存在
/// </summary>
/// <param name="strSql"></param>
/// <returns></returns>
public static bool Exists(string strSql)
{
object obj = GetSingle(strSql);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = ;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == )
{
return false;
}
else
{
return true;
}
}
/// <summary>
/// 是否存在（基于MySqlParameter）
/// </summary>
/// <param name="strSql"></param>
/// <param name="cmdParms"></param>
/// <returns></returns>
public static bool Exists(string strSql, params MySqlParameter[] cmdParms)
{
object obj = GetSingle(strSql, cmdParms);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = ;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == )
{
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 (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(SQLString, connection))
{
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
} public static int ExecuteSqlByTime(string SQLString, int Times)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(SQLString, connection))
{
try
{
connection.Open();
cmd.CommandTimeout = Times;
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
} /// <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(List<String> SQLStringList)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = conn;
MySqlTransaction tx = conn.BeginTransaction();
cmd.Transaction = tx;
try
{
int count = ;
for (int n = ; n < SQLStringList.Count; n++)
{
string strsql = SQLStringList[n];
if (strsql.Trim().Length > )
{
cmd.CommandText = strsql;
count += cmd.ExecuteNonQuery();
}
}
tx.Commit();
return count;
}
catch
{
tx.Rollback();
return ;
}
}
}
/// <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 (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand(SQLString, connection);
MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@content", SqlDbType.NText);
myParameter.Value = content;
cmd.Parameters.Add(myParameter);
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
finally
{
cmd.Dispose();
connection.Close();
}
}
}
/// <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 (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand(SQLString, connection);
MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@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 (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
finally
{
cmd.Dispose();
connection.Close();
}
}
}
/// <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 (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand(strSQL, connection);
MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@fs", SqlDbType.Image);
myParameter.Value = fs;
cmd.Parameters.Add(myParameter);
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
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 (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(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 (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
}
public static object GetSingle(string SQLString, int Times)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(SQLString, connection))
{
try
{
connection.Open();
cmd.CommandTimeout = Times;
object obj = cmd.ExecuteScalar();
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
return null;
}
else
{
return obj;
}
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
}
/// <summary>
/// 执行查询语句，返回MySqlDataReader ( 注意：调用该方法后，一定要对MySqlDataReader进行Close )
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>MySqlDataReader</returns>
public static MySqlDataReader ExecuteReader(string strSQL)
{
MySqlConnection connection = new MySqlConnection(connectionString);
MySqlCommand cmd = new MySqlCommand(strSQL, connection);
try
{
connection.Open();
MySqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
return myReader;
}
catch (MySql.Data.MySqlClient.MySqlException 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 (MySqlConnection connection = new MySqlConnection(connectionString))
{
DataSet ds = new DataSet();
try
{
connection.Open();
MySqlDataAdapter command = new MySqlDataAdapter(SQLString, connection);
command.Fill(ds, "ds");
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
public static DataSet Query(string SQLString, int Times)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
DataSet ds = new DataSet();
try
{
connection.Open();
MySqlDataAdapter command = new MySqlDataAdapter(SQLString, connection);
command.SelectCommand.CommandTimeout = Times;
command.Fill(ds, "ds");
}
catch (MySql.Data.MySqlClient.MySqlException 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 MySqlParameter[] cmdParms)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand())
{
try
{
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
int rows = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
}
}
} /// <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MySqlParameter[]）</param>
public static void ExecuteSqlTran(Hashtable SQLStringList)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
using (MySqlTransaction trans = conn.BeginTransaction())
{
MySqlCommand cmd = new MySqlCommand();
try
{
//循环
foreach (DictionaryEntry myDE in SQLStringList)
{
string cmdText = myDE.Key.ToString();
MySqlParameter[] cmdParms = (MySqlParameter[])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MySqlParameter[]）</param>
public static int ExecuteSqlTran(System.Collections.Generic.List<CommandInfo> cmdList)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
using (MySqlTransaction trans = conn.BeginTransaction())
{
MySqlCommand cmd = new MySqlCommand();
try
{ int count = ;
//循环
foreach (CommandInfo myDE in cmdList)
{
string cmdText = myDE.CommandText;
MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Parameters;
PrepareCommand(cmd, conn, trans, cmdText, cmdParms); if (myDE.EffentNextType == EffentNextType.WhenHaveContine || myDE.EffentNextType == EffentNextType.WhenNoHaveContine)
{
if (myDE.CommandText.ToLower().IndexOf("count(") == -)
{
trans.Rollback();
return ;
} object obj = cmd.ExecuteScalar();
bool isHave = false;
if (obj == null && obj == DBNull.Value)
{
isHave = false;
}
isHave = Convert.ToInt32(obj) > ; if (myDE.EffentNextType == EffentNextType.WhenHaveContine && !isHave)
{
trans.Rollback();
return ;
}
if (myDE.EffentNextType == EffentNextType.WhenNoHaveContine && isHave)
{
trans.Rollback();
return ;
}
continue;
}
int val = cmd.ExecuteNonQuery();
count += val;
if (myDE.EffentNextType == EffentNextType.ExcuteEffectRows && val == )
{
trans.Rollback();
return ;
}
cmd.Parameters.Clear();
}
trans.Commit();
return count;
}
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MySqlParameter[]）</param>
public static void ExecuteSqlTranWithIndentity(System.Collections.Generic.List<CommandInfo> SQLStringList)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
using (MySqlTransaction trans = conn.BeginTransaction())
{
MySqlCommand cmd = new MySqlCommand();
try
{
int indentity = ;
//循环
foreach (CommandInfo myDE in SQLStringList)
{
string cmdText = myDE.CommandText;
MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Parameters;
foreach (MySqlParameter q in cmdParms)
{
if (q.Direction == ParameterDirection.InputOutput)
{
q.Value = indentity;
}
}
PrepareCommand(cmd, conn, trans, cmdText, cmdParms);
int val = cmd.ExecuteNonQuery();
foreach (MySqlParameter q in cmdParms)
{
if (q.Direction == ParameterDirection.Output)
{
indentity = Convert.ToInt32(q.Value);
}
}
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MySqlParameter[]）</param>
public static void ExecuteSqlTranWithIndentity(Hashtable SQLStringList)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
using (MySqlTransaction trans = conn.BeginTransaction())
{
MySqlCommand cmd = new MySqlCommand();
try
{
int indentity = ;
//循环
foreach (DictionaryEntry myDE in SQLStringList)
{
string cmdText = myDE.Key.ToString();
MySqlParameter[] cmdParms = (MySqlParameter[])myDE.Value;
foreach (MySqlParameter q in cmdParms)
{
if (q.Direction == ParameterDirection.InputOutput)
{
q.Value = indentity;
}
}
PrepareCommand(cmd, conn, trans, cmdText, cmdParms);
int val = cmd.ExecuteNonQuery();
foreach (MySqlParameter q in cmdParms)
{
if (q.Direction == ParameterDirection.Output)
{
indentity = Convert.ToInt32(q.Value);
}
}
cmd.Parameters.Clear();
}
trans.Commit();
}
catch
{
trans.Rollback();
throw;
}
}
}
}
/// <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 MySqlParameter[] cmdParms)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand())
{
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 (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
}
}
} /// <summary>
/// 执行查询语句，返回MySqlDataReader ( 注意：调用该方法后，一定要对MySqlDataReader进行Close )
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>MySqlDataReader</returns>
public static MySqlDataReader ExecuteReader(string SQLString, params MySqlParameter[] cmdParms)
{
MySqlConnection connection = new MySqlConnection(connectionString);
MySqlCommand cmd = new MySqlCommand();
try
{
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
MySqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return myReader;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
// finally
// {
// cmd.Dispose();
// connection.Close();
// } } /// <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 MySqlParameter[] cmdParms)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand();
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
using (MySqlDataAdapter da = new MySqlDataAdapter(cmd))
{
DataSet ds = new DataSet();
try
{
da.Fill(ds, "ds");
cmd.Parameters.Clear();
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
} private static void PrepareCommand(MySqlCommand cmd, MySqlConnection conn, MySqlTransaction trans, string cmdText, MySqlParameter[] 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 (MySqlParameter parameter in cmdParms)
{
if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
(parameter.Value == null))
{
parameter.Value = DBNull.Value;
}
cmd.Parameters.Add(parameter);
}
}
} #endregion } }
关于MySql的DBHelper类以及数据分页的更多相关文章
- 关于SqlServer的DBHelper类以及数据分页
前端: <My:AspNetPager class="arPage" PageSize="20" UrlPaging="true" r ...
- Accesss数据库的DBhelper类（带分页）
首先配置web.config,使配置文件连接access数据库: <connectionStrings> <add name="DBConnection" con ...
- 数据分页jdbc+mysql实现
通过简单粗糙的功能不完善的客户管理案例体现jdbc+mysql的数据分页,与其说是管理系统,不如说就是一个jdbc数据分布的demo而已.但是话又说回来,麻雀虽小,五脏俱全.虽然是个小demo,但是其 ...
- 原生PHP实现Mysql数据分页功能
一. 思路整理 实现一个数据分页功能,需要有数据的总条数,每页展示的条数,和当前在第几页这三个参数 通过⌈总条数/每页展示的条数⌉可以得到总页数,比如某留言板有101条留言,每页展示10条,一那就需要 ...
- Oracle、MySql、SQLServer数据分页查询
看过此博文后Oracle.MySql.SQLServer 数据分页查询,在根据公司的RegionRes表格做出了 SQLserver的分页查询语句: 别名.字段 FROM( SELECT row_nu ...
- Oracle、MySql、SQLServer 数据分页查询
最近简单的对oracle,mysql,sqlserver2005的数据分页查询作了研究,把各自的查询的语句贴出来供大家学习..... (一). mysql的分页查询 mysql的分页查询是最简单的,借 ...
- MapReduce 程序mysql JDBC驱动类找不到原因及学习hadoop写入数据到Mysql数据库的方法
报错 :ClassNotFoundException: com.mysql.jdbc.Driver 需求描述: hadoop需要动态加载个三方jar包(比如mysql JDBC 驱动包),是在MR结束 ...
- mysql 大数据分页优化
一.mysql大数据量使用limit分页,随着页码的增大,查询效率越低下. 1. 直接用limit start, count分页语句, 也是我程序中用的方法: select * from prod ...
- 转Oracle、MySql、SQLServer 数据分页查询
最近简单的对oracle,mysql,sqlserver2005的数据分页查询作了研究,把各自的查询的语句贴出来供大家学习..... (一). mysql的分页查询 mysql的分页查询是最简单的,借 ...
随机推荐
- android mvvm
android studio 需要gradle 1.5.0以上才支持 dependencies { classpath 'com.android.tools.build:gradle:1.5.0'} ...
- Apriori原理与实践
Apriori: 其核心思想是通过候选集生成和情节的向下封闭检测两个阶段来挖掘频繁项集.经典的关联规则数据挖掘算法Apriori 算法广泛应用于各种领域,通过对数据的关联性进行了分析和挖掘,挖掘出的这 ...
- Client默认用户及登录密码（转）
Client默认用户及登录密码 SAP系统(如ERP.CRM等)安装完成,初始化状态下有若干个客户端(Client).如果是生产系统,一般只有000.001.066等三个Client:如果是IDES系 ...
- C++编程优化心得（持续更新）
1. 对齐原则.比如64位总线,每次寻址读取8B.编程时注意变量地址,尽量消耗总线最少的寻址次数.堆内存申请时,系统严格按照对齐原则分配,故而使用时候也尽量不要跨寻址边界. 2. 需要的时候,可为了效 ...
- 变量声明提升 Vs. 函数声明提升
1. 变量声明提升 先看以下代码: 1)var in_window = "a" in window; console.log(in_window); 2)var in_window ...
- excel列递增方法技巧
最近处理世界买家网100多万的数据,需要用到excel来对数据进行处理,其中有一项是对数据做一个排序,以方便数据导入时来对应唯一的id编号,之前都是 几万,最多也是30来万的数据,所以列递增就直接用鼠 ...
- JavaScript基础--面向对象三大特性（八）：继承封装多态
一.构造函数基本用法:function 类名(参数列表){ 属性=参数值} function Person(name,age){ this.name = name; this.age = age; } ...
- zip函数
zip函数接受任意多个(包括0个和1个)序列作为参数,返回一个包含元组的列表. x = [1, 2, 3] y = [4, 5, 6] z = [7, 8, 9] xyz = zip(x, y, z) ...
- 利用Arduino快速制作Teensy BadUSB
0×00 介绍 本文想以较简单的方式,叙述Arduino版BadUSB的制作过程.我知道在这之前已经有很多前辈都写过相关的文章,但小白可能还有点迷糊,所以这篇文章是快速带大家入门了解,我也是菜B大神不 ...
- windows核心编程---第七章 用户模式下的线程同步
用户模式下的线程同步 系统中的线程必须访问系统资源,如堆.串口.文件.窗口以及其他资源.如果一个线程独占了对某个资源的访问,其他线程就无法完成工作.我们也必须限制线程在任何时刻都能访问任何资源.比如在 ...