IBatisNet 之 自动生成主关键字

很多系统支持自动生成主关键字。一些数据库厂商预先生成 (oracle) ，一些数据库厂商之后生成 (mssal mysql). 。如果你在 <insert> 元素中使用 <selectKey> 节，你就能获得一个预先生成的 key. 。下面的例子演示了这种方法：

<!―Oracle SEQUENCE Example --> <insert id="insertProduct-ORACLE"         parameterClass="product">       <selectKey resultClass="int"        Property="id" > SELECT STOCKIDSEQUENCE.NEXTVAL AS ID FROM DUAL         </selectKey> insert into PRODUCT (PRD_ID,PRD_DESCRIPTION) values         (#id#,#description#) </insert>    <!― Microsoft SQL Server IDENTITY Column Example --> <insert id="insertProduct-MS-SQL"         parameterClass="product"> insert into PRODUCT (PRD_DESCRIPTION)         values (#description#) <selectKey resultClass="int"         Property="id" > SELECT @@IDENTITY AS ID </selectKey>         </insert>

上面是IbatisNet的 iBATIS Data Mapper Developer Guide上的说明：下面来介绍一下具体的应用和注意的地方：
person.xml
?xml version="1.0" encoding="utf-8" ?>

<sqlMap
 namespace="Person"
 xmlns:xsi=" [url]http://www.w3.org/2001/XMLSchema-instance[/url]"
 xsi:noNamespaceSchemaLocation="SqlMap.xsd">

 <!-- XML "behind" document for the People service class. -->

 <alias>
  <typeAlias alias="Person" type="IbatisTest.Domain.Person, IbatisTest.Domain" />
 </alias>
 
 <resultMaps>
  <resultMap id="SelectResult" class="Person">
   <result property="Id" column="PER_ID" />
   <result property="FirstName" column="PER_FIRST_NAME" />
   <result property="LastName" column="PER_LAST_NAME" />
   <result property="BirthDate" column="PER_BIRTH_DATE" />
   <result property="WeightInKilograms" column="PER_WEIGHT_KG" />
   <result property="HeightInMeters" column="PER_HEIGHT_M" />
  </resultMap>
 </resultMaps>
 
  <insert id="Insert" parameterClass="Person">
   insert into PERSON
    (PER_FIRST_NAME, PER_LAST_NAME,
    PER_BIRTH_DATE, PER_WEIGHT_KG, PER_HEIGHT_M)
   values
    ( #FirstName#, #LastName#,
    #BirthDate#, #WeightInKilograms#, #HeightInMeters#)
   <selectKey property="Id" type="post" resultClass="int"> 
   select CAST(@@IDENTITY as int) as value
   </selectKey> 
  </insert>    
   </statements>
 
</sqlMap> 
<selectKey> 节返回一个从 sql server 生成的自动生成关键字。     
             //新增一个员工
             private void Button1_Click(object sender, System.EventArgs e)  
          {  
              IbatisTest.Domain.Person person = new IbatisTest.Domain.Person();  
              person.Id =-1;//这里的赋值很重要，否则会出错
              person.FirstName = "--New Person--";
                     person.BirthDate = Convert.ToDateTime("2000-4-2");    
              PersonHelper personhelper = new PersonHelper();  
                     personhelper.Insert(person);  
         }  

          //业务逻辑类方法
          public int Insert (Person person) 
          {
              try
              {

                   int result = -1;

                    result =(int)Mapper().Insert("Insert",person);

                   return result;

              }
             catch(Exception ex) 
              {

                   throw ex; 
              }

         }

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