SQLCLR(四)用户定义类型UDT
用户自定义类型是SQL Server 2005的新特性。和前几篇文章介绍的SQLCLR相比,UDT相对有此复杂。UDT也有许多限制和必须遵守UDT规范。UDT的二进制不能超过8000个字节,必须包含一个null值表示,因为SQLServer的数据类型是允许null值的。
UDT可以是结构或类。如果是类的话需加[StructLayout(LayoutKind.Sequential)]
标签(属性),这是保证序列化时不改变属性的次序。
现在看一段代码
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using System;
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using System.IO;
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using System.Data;
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using System.Data.SqlClient;
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using System.Data.SqlTypes;
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using Microsoft.SqlServer.Server;
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[Serializable]
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[Microsoft.SqlServer.Server.SqlUserDefinedType(Format.UserDefined, MaxByteSize = 1024)]
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public struct Person : INullable, IBinarySerialize
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{
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public override string ToString()
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{
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// 用您的代码替换下列代码
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return FormatU();
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}
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public bool IsNull
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{
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get
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{
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// 在此处放置代码
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return m_Null;
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}
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}
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public static Person Null
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{
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get
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{
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Person h = new Person();
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h.m_Null = true;
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return h;
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}
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}
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public static Person Parse(SqlString s)
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{
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if (s.IsNull)
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return Null;
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Person u = new Person();
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string value = s.Value;
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if (value == "null") return Null;
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string[] parts = value.Split(',');
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u.name = parts[0];
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u.age = ParseAge(parts[1]);
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u.sex = parts[2];
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return u;
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}
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// 这是占位符方法
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public string FormatU()
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{
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//在此处插入方法代码
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return string.Format("名称:{0},年龄:{1},性别:{2}", name, age, sex);
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}
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// 这是占位符静态方法
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public static int ParseAge(string str)
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{
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//在此处插入方法代码
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return int.Parse(str.Substring(0, str.LastIndexOf("岁")));
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}
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// 这是占位符字段成员
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private int age;
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public int Age
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{
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get ![](https://www.cnblogs.com/Images/dot.gif)
{ return age; }
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set ![](https://www.cnblogs.com/Images/dot.gif)
{ age = value; }
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}
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private string name;
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public string Name
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{
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get ![](https://www.cnblogs.com/Images/dot.gif)
{ return name; }
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set ![](https://www.cnblogs.com/Images/dot.gif)
{ name = value; }
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}
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private string sex;
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public string Sex
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{
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get ![](https://www.cnblogs.com/Images/dot.gif)
{ return sex; }
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set ![](https://www.cnblogs.com/Images/dot.gif)
{ sex = value; }
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}
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// 私有成员
UDT可以是结构或类。如果是类的话需加[StructLayout(LayoutKind.Sequential)]
标签(属性),这是保证序列化时不改变属性的次序。
现在看一段代码
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
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