isNull判斷property欄位是否是null
isEmpty判斷property欄位 是否是null 和 空字串
isEqual相當於equals，數字用得多些，一般都是判斷狀態值

例子1:(isEqual)

<isEqual property="state" compareValue="0">< /isEqual>
或
<isEqual property="state" compareProperty="nextState"></isEqual>

例子2：
傳入的map或者類的屬性name等於”1”嗎，是就附加and和vvvv

<isEqual property="name" compareValue="1" prepend="and">
    vvvv = '哈哈'
< /isEqual>

傳入的map或者類的屬性name是null嗎，是就附加and和vvvv = null

< isNull property="name" prepend="and">
    vvvv = null
< /isNull>

sqlmap

<select id="querySingleModelByOut"  parameterClass="com.hanpeng.base.phone.model.TBussinessNotice"
 
   
    resultClass="com.hanpeng.base.phone.model.TBussinessNotice">  
    select * from (select row_.*, rownum rownum_ from (  
        SELECT  
            i.NOTICE_NUM  as noticeNum ,              
            i.BUSSINESS_ID  as bussinessId ,              
            i.STATE  as state ,           
            i.READ_DATE  as
 
 readDate ,  
            n.NOTICE_TITLE as noticeTitle ,           
            n.NOTICE_INFO as noticeInfo ,             
            n.CREATE_DATE as createDate ,             
            n.EMPLOYEE_ID as employeeId ,             
            n.NOTICE_TYPE as noticeType ,             
            n.NOTICE_SHOW_TYPE as noticeShowType ,            
            n.FINISH_DATE as finishDate ,             
            n.PUBLISH_DATE as publishDate   
        FROM  T_BUSSINESS_NOTICE i left join T_NOTICE n on n.NOTICE_NUM = i.NOTICE_NUM   
        WHERE  
        n.PUBLISH_DATE &lt;= sysdate AND n.FINISH_DATE &gt;= sysdate  
        <isNotEmpty prepend=" AND " property="bussinessId">   
            i.BUSSINESS_ID = #bussinessId# </isNotEmpty>  
        <isNotEmpty prepend=" AND " property="state">   
            i.STATE = #state# </isNotEmpty>  
        <isNotEmpty prepend=" AND " property="noticeShowType">   
            n.NOTICE_SHOW_TYPE = #noticeShowType# </isNotEmpty>  
        <isEqual property="saleBack" compareValue="10" prepend=" AND ">  
            n.NOTICE_TYPE!='25'</isEqual>  
        <isEqual property="remittanceBank" compareValue="10" prepend=" AND ">  
            n.NOTICE_TYPE!='63'</isEqual>  
        <isEqual property="remittanceOnline" compareValue="10" prepend=" AND ">  
            n.NOTICE_TYPE!='64'</isEqual>  
    )row_ where rownum &lt;=1 ) where rownum_&gt;=0  
</select>