/// <summary> /// 账面数据 Accounting /// </summary> /// <returns></returns> DataTable setDataAccounting() { DataTable dt = new DataTable(); dt.Columns.Add("id", typeof(int)); dt.Columns.Add("empno", typeof(string))…

前言 本节我们来综合比较NOT IN VS NOT EXISTS VS LEFT JOIN...IS NULL的性能,简短的内容,深入的理解,Always to review the basics. NOT IN.NOT EXISTS.LEFT JOIN...IS NULL性能分析 我们首先创建测试表 USE TSQL2012 GO CREATE SCHEMA [compare] CREATE TABLE [compare].t_left ( id INT NOT NULL PRIMARY KE…

(function () { //check the class name , it will be replaced when existed if (window.IQCBase) { //return window.IQCBase; //window._IQCBase = window.IQCBase; } //constructor window.IQCBase = function (param) { param = param instanceof Object ? param :…

from http://www.akadia.com/services/ora_chained_rows.html Overview If you notice poor performance in your Oracle database Row Chaining and Migration may be one of several reasons, but we can prevent some of them by properly designing and/or diagnosin…

下面有例子说明: 首先我们需要打开一个联结: string MyConnString = "Driver={Microsoft Access Driver (*.mdb)}; DBQ=c:/test/test.mdb;"; string strComm = "select * from UserList"; ADOConnection MyConnection = new ADOConnection(MyConnString); ADODataSetCommand…

SQL 1. 现有一张学生表,有只有一个列是名字,请选出其中的重名的学生的名字select name from student group by name having count(*) > 1 2. 从公司员工工资表中选出所有部门平均工资大于公司平均工资的部门里的所有员工记录 select * from company where department in (select department from company group by deparment having avg(salary…

什么是数据库事务? 数据库事务_百度百科 https://baike.baidu.com/item/%E6%95%B0%E6%8D%AE%E5%BA%93%E4%BA%8B%E5%8A%A1/9744607?fr=aladdin 一个逻辑工作单元要成为事务,必须满足所谓的ACID(原子性(atomicity,或称不可分割性).一致性(consistency).隔离性(isolation,又称独立性).持久性(durability))属性. 索引如何实现? 数据库索引_百度百科 https://b…

DataTable dt = setData(); // Sum rows. //foreach (DataRow row in dt.Rows) //{ // int rowTotal = 0; // foreach (DataColumn col in row.Table.Columns) // { // Console.WriteLine(row[col]); // rowTotal += Int32.Parse(row[col].ToString()); // } // Console.…

/// <summary> /// 涂聚文 /// 2011 捷为工作室 /// 缔友计算机信息技术有限公司 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> protected void Page_Load(object sender, EventArgs e) { this.Page.T…

序言 MangoDB CSharp Driver是c#操作mongodb的官方驱动. 官方Api文档:http://api.mongodb.org/csharp/2.2/html/R_Project_CSharpDriverDocs.htm#! 驱动的具体介绍:https://docs.mongodb.org/ecosystem/drivers/csharp/ 本文主要对c#操作mongodb的增删改查,以及数据库链接配置做代码示例,方便进一步封装及学习. mongodb链接配置 public…