oracle中rownum的使用

简单的说：oracle中同时使用rownum和order by时，要对子查询用order by，对父查询用rownum

代码示例：

<!-- 根据判重时的数据查找ins主键 使用rownum并需要排序的话，必须先用子查询进行排序-->

<select id="selectPkInsId"

parameterClass="com.sinosig.premiumServicebus.bean.Client_Message"

resultClass="java.lang.Long">

select i.pk_t_ins_id from ( select info.pk_t_ins_id from

t_se_insurance_info info where info.cont_tel = #body.CONTTEL#

<dynamic>

<!-- 是新车 -->

<isEqual prepend="" property="body.NEWVEHICLE"

compareValue="1">

<isNotEmpty prepend="and" property="body.CONTNAME">

cont_name=#body.CONTNAME#

</isNotEmpty>

</isEqual>

<!-- 非新车 -->

<isEqual prepend="" property="body.NEWVEHICLE"

compareValue="0">

<isNotEmpty prepend="and" property="body.LICENSENO">

num_plate=#body.LICENSENO#

</isNotEmpty>

</isEqual>

<isNotEqual prepend="and" property="body.agentCode"

compareValue="00000000">

substr(info.purgecode,0,2) = 'DM'

</isNotEqual>

<isEqual prepend="and" property="body.agentCode"

compareValue="00000000">

substr(info.purgecode,0,2) = 'WB'

</isEqual>

</dynamic>

order by info.pk_t_ins_id desc ) i where rownum = 1

</select>
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