昨天帮朋友做了个小工具,以完成多表连接处理一些数据。今天下班后又做了份使用文档,不知友能看懂否?现将使用文档及源码发布如下,以供有同样需求的朋友下载。
INSERT INTO [Employee$](EmployeeId,EmployeeName,BranchId) VALUES('YG2014120001','韩兆新','BM20141201');
执行Sql前:
执行Sql后:
UPDATE [Employee$] SET BranchId = 'BM20141202';
执行Sql前:
执行Sql后:
SELECT EmployeeId,EmployeeName,BranchId FROM [Employee$];
显然不支持!
UPDATE [Employee$] SET EmployeeID=null,EmployeeName=null,BranchId=null WHERE EmployeeID='YG2014120003';
执行Sql前:
执行Sql后:
SELECT EmployeeId,EmployeeName,BranchId FROM [Employee$] WHERE EmployeeID = 'YG2014120002';
SELECT * FROM [Employee$] WHERE EmployeeID LIKE 'YG201412%';
1、*:所有列的名称;
2、%:通配n个字符;
3、_:通配1个字符。
1、升序:(ASC)可省略;
2、降序:(DSEC)。
示例1:(升序排序)
SELECT * FROM [Employee$] ORDER BY EmployeeId DESC;
示例2:(降序排序)
SELECT * FROM [Employee$] ORDER BY EmployeeId DESC;
示例3:(升序排序简写)
SELECT * FROM [Employee$] ORDER BY EmployeeId;
先建立两个用于演示的sheet:
Characters:
ID | Character |
1 | 内向 |
2 | 外向 |
3 | 中性性格 |
Colors:
ID | Color |
1 | 绿色 |
2 | 红色 |
4 | 蓝色 |
内连接(JOIN 或 INNER JOIN):内连接取交集
示意图:
SELECT * FROM [characters$] INNER JOIN [colors$] ON [characters$].ID = [colors$].ID;
外连接可分为:左连接、右连接、完全外连接。
示意图:
SELECT * FROM [characters$] LEFT JOIN [colors$] ON [characters$].ID = [colors$].ID;
结果:
示意图:
SELECT * FROM [characters$] RIGHT JOIN [colors$] ON [characters$].ID = [colors$].ID;
结果:
示意图:
SELECT * FROM [characters$] LEFT JOIN [colors$] ON [characters$].ID = [colors$].ID
UNION
SELECT * FROM [characters$] RIGHT JOIN [colors$] ON [characters$].ID = [colors$].ID;
结果:
交叉连接产生连接所涉及的表的笛卡尔积。
SELECT * FROM [characters$],[colors$];
结果:
SELECT * FROM [characters$],[colors$] WHERE [characters$].ID = [colors$].ID;
SELECT * FROM [characters$],[colors$];
PRogram.cs
using System;
using System.IO;
using System.Windows.Forms;
namespace SqlExcel
{
static class Program
{
/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Sunisoft.IrisSkin.SkinEngine skinEngine = new Sunisoft.IrisSkin.SkinEngine();
string skinPath = application.StartupPath + Path.DirectorySeparatorChar + "skin" + Path.DirectorySeparatorChar + "skin.ssk";
skinEngine.SkinFile = skinPath;
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MainForm());
}
}
}
MainForm.cs
using System;
using System.Data;
using System.Data.Common;
using System.Drawing;
using System.Windows.Forms;
namespace SqlExcel
{
新闻热点
疑难解答