DLINQ练习

以前做过一个NHibernate练习，这里用DLINQ重新来过

 

0. 安装参考</p> <p>The LINQ Project<br /> http://msdn.microsoft.com/netframework/future/linq/</p> <ol> <li>生成数据库</li> </ol> <p>use master<br /> go<br /> create database DLINQ<br /> go<br /> use DLINQ<br /> go<br /> CREATE TABLE users (<br /> LogonID nvarchar(20) NOT NULL default ‘0’,<br /> Name nvarchar(40) default NULL,<br /> Password nvarchar(20) default NULL,<br /> EmailAddress nvarchar(40) default NULL,<br /> LastLogon datetime default NULL,<br /> PRIMARY KEY (LogonID)<br /> )<br /> go</p><div class='code-block code-block-3' style='margin: 8px 0; clear: both;'> <script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <ins class="adsbygoogle" style="display:block; text-align:center;" data-ad-layout="in-article" data-ad-format="fluid" data-ad-client="ca-pub-6768214833031159" data-ad-slot="4803962711"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script></div> <ol> <li>使用SqlMetal生成Entity Class: User.cs</li> </ol> <p>SqlMetal /server:(local) /database:DLINQ /delayfetch /pluralize /namespace:LINQ.Examples.QuickStart /code:User.cs</p> <p>//——————————————————————————<br /> // <auto-generated><br /> // This code was generated by a tool.<br /> // Runtime Version:2.0.50215.44<br /> //<br /> // Changes to this file may cause incorrect behavior and will be lost if<br /> // the code is regenerated.<br /> // </auto-generated><br /> //——————————————————————————</p> <p>namespace LINQ.Examples.QuickStart {<br /> using System;<br /> using System.Collections.Generic;<br /> using System.Data.DLinq;</p> <p>public partial class DLINQ : DataContext {</p> <pre><code>public Table&lt;User&gt; Users; public DLINQ() { } public DLINQ(string connection) : base(connection) { } </code></pre> <p>}</p> <p>[Table(Name=”users”)]<br /> public partial class User : System.Data.DLinq.IChangeNotifier {</p> <pre><code>private string _LogonID; private string _Name; private string _Password; private string _EmailAddress; private System.Nullable&lt;System.DateTime&gt; _LastLogon; public User() { } [Column(Storage="_LogonID", DbType="NVarChar(20) NOT NULL", Id=true)] public string LogonID { get { return this._LogonID; } set { if ((this._LogonID != value)) { this.OnChanging(); this._LogonID = value; } } } [Column(Storage="_Name", DbType="NVarChar(40)")] public string Name { get { return this._Name; } set { if ((this._Name != value)) { this.OnChanging(); this._Name = value; } } } [Column(Storage="_Password", DbType="NVarChar(20)")] public string Password { get { return this._Password; } set { if ((this._Password != value)) { this.OnChanging(); this._Password = value; } } } [Column(Storage="_EmailAddress", DbType="NVarChar(40)")] public string EmailAddress { get { return this._EmailAddress; } set { if ((this._EmailAddress != value)) { this.OnChanging(); this._EmailAddress = value; } } } [Column(Storage="_LastLogon", DbType="DateTime")] public System.Nullable&lt;System.DateTime&gt; LastLogon { get { return this._LastLogon; } set { if ((this._LastLogon != value)) { this.OnChanging(); this._LastLogon = value; } } } public event System.Data.DLinq.ObjectChangingEventHandler ObjectChanging; private void OnChanging() { if ((this.ObjectChanging != null)) { this.ObjectChanging(this, System.EventArgs.Empty); } } </code></pre> <p>}<br /> }</p> <ol> <li>生成测试程序:TestUser.cs</li> </ol> <p>using System;<br /> using System.Collections.Generic;<br /> using System.Data.DLinq;<br /> using System.Query;</p> <p>using LINQ.Examples.QuickStart;</p> <p>class TestUser<br /> {<br /> public static void Main()<br /> {</p> <pre><code>DLINQ db = new DLINQ("server=(local);database=DLINQ;uid=sa;pwd=;"); User newUser = new User(); newUser.LogonID = "joe_cool"; newUser.Name = "Joseph Cool"; newUser.Password = "abc123"; newUser.EmailAddress = "joe@cool.com"; newUser.LastLogon = DateTime.Now; db.Users.Add(newUser); db.SubmitChanges(); Console.WriteLine("go check in the database, enter return to continue...."); Console.ReadLine(); var userExpr = from u in db.Users where u.LogonID == "joe_cool" select u; User joeCool = userExpr.First(); joeCool.LastLogon = DateTime.Now; db.SubmitChanges(); userExpr = from u in db.Users select u; foreach(var user in userExpr) { Console.WriteLine(user.LogonID + " last logged in at " + user.LastLogon); } userExpr = from u in db.Users where u.LastLogon &gt; new DateTime(2004, 03, 14, 20, 0, 0) select u; foreach(var user in userExpr) { Console.WriteLine(user.LogonID + " last logged in at " + user.LastLogon); } </code></pre> <p>}<br /> }</p> <ol> <li>compile TestUser.cs:</li> </ol> <p>D:\Program Files\LINQ Preview\Bin>.\csc /r:.\System.Query.dll;.\System.Data.DLinq.dll TestUser.cs User.cs</p> <ol> <li>run TestUser.exe</li> </ol> <p>D:\Program Files\LINQ Preview\Bin>TestUser<br /> go check in the database, enter return to continue….</p> <p>joe_cool last logged in at 2005-9-16 10:45:102005-9-16 10:45:10<br /> joe_cool last logged in at 2005-9-16 10:45:102005-9-16 10:45:10</p> <p>

想试的话，也许需要改动连接字符串，可惜上面的程序在8月份的CTP上不工作。出錯信息是

Unhandled Exception: System.TypeLoadException: Could not load type ‘System.INullableValue’ from assembly ‘mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’.
   at System.Data.DLinq.SqlClient.QueryConverter.IsConstNull(ConstantExpression expr)
   at System.Data.DLinq.SqlClient.QueryConverter.VisitConstant(ConstantExpression cons) in c:\PdcBuild\query\DLinq\Engine\Converter.cs:line 500
   at System.Data.DLinq.SqlClient.QueryConverter.VisitInner(Expression node) in c:\PdcBuild\query\DLinq\Engine\Converter.cs:line 102……