Mybatis中 SQL语句复用

mapper.xml *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

<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