mapper.xml 中共用
mapper.xml 间共用
项目中也许我们会遇到一段sql语句被多个查询、增加等语句用到的情况，如何去偷懒呢，复用sql无疑是较好的选择
这里只提供简单的示范：
如果只是单表查询，并且希望共用的sql只会出现在同一个mapper.xml文件中，那么我们可以直接在
<mapper namespace="xxxxx"></mapper>
中写下面的业务代码
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<sql id="unitsql">
a.userid,a.legalcode,legalname,
biddercodetype,legalrole,
licenseno,date_format(licenseenddate,"%y-%m-%d") as licenseenddate,
taxcertno,date_format(taxcertenddate,"%y-%m-%d") as taxcertenddate,
localtaxcertno,date_format(localtaxcertenddate,"%y-%m-%d") as localtaxcertenddate,
organno,date_format(organcertenddate,"%y-%m-%d") as organcertenddate,
legalrepresent,legaltype,
perresentphone,legalindustary,creditrate,
countryregion,legalunitaddress,regioncode,registerprovince,
a.regcapital,a.regcapcurrency,a.regunit,
registercity,registercounty,basicbank,basicbranchbank,
basicaccountno,basicaccountname,legalcontact,legalcontactphone,
legalcontactaddress,legalweb,legalzipcode,legalemail,
legalstatus
</sql>
然后引用
<select id="gettenderagentbyid" parametertype="string" resulttype="map">
select <include refid="unitsql"/>, -- 就是这句话引用 ，refid为共有sql语句id
b.auditopinion,b.createuser,
b.createtime,
b.lastupdateuser,
b.lastupdatetime,
b.disabled,b.infostatus
from p_legalunit a, p_tenderagent b
where b.userid=#{userid} and a.userid = b.userid and b.disabled='0'
</select>
如果是连表查询，那么我们极有可能会希望有一个sql语句被多个mapper.xml引用的的方法，很简单。
我们可以新建一个mapper.xml文件（当然，这个mapper.xml要在你的扫描路径下，本文不赘述）。取名为common.xml
该文件内容为
<?xml version="1.0" encoding="utf-8"?>
<!doctype mapper public "-//mybatis.org//dtd mapper 3.0//en" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="common">
<sql id="common.unitsql">
a.userid,a.legalcode,legalname,
biddercodetype,legalrole,
licenseno,date_format(licenseenddate,"%y-%m-%d") as licenseenddate,
taxcertno,date_format(taxcertenddate,"%y-%m-%d") as taxcertenddate,
localtaxcertno,date_format(localtaxcertenddate,"%y-%m-%d") as localtaxcertenddate,
organno,date_format(organcertenddate,"%y-%m-%d") as organcertenddate,
legalrepresent,legaltype,
perresentphone,legalindustary,creditrate,
countryregion,legalunitaddress,regioncode,registerprovince,
a.regcapital,a.regcapcurrency,a.regunit,
registercity,registercounty,basicbank,basicbranchbank,
basicaccountno,basicaccountname,legalcontact,legalcontactphone,
legalcontactaddress,legalweb,legalzipcode,legalemail,
legalstatus
</sql>
</mappper>
在另一个mapper.xml文件引用
<select id="gettenderagentbyid" parametertype="string" resulttype="map">
select <include refid="common.unitsql"/>, -- 就是这句话引用 ，refid为共有sql语句id
b.auditopinion,b.createuser,
b.createtime,
b.lastupdateuser,
b.lastupdatetime,
b.disabled,b.infostatus
from p_legalunit a, p_tenderagent b
where b.userid=#{userid} and a.userid = b.userid and b.disabled='0'
</select>
==注:为何我的文件名要取为common.xml并且id也为common.unitsql呢？这是为了后期维护方便，如此，可以更容易找到该共有的sql在哪一个文件==
以上所述是小编给大家介绍的mybatis中 sql语句复用，希望对大家有所帮助
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