数据库和ORM如何优雅的添加字段？

RT，业务需要为某个实体添加字段，如何在生成了Mybatis XML（包含了手写的部分联合查询）的情况下优雅的添加字段呢？

作者：方小葱
链接：https://www.zhihu.com/question/284511416/answer/438123378
来源：知乎
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我非常讨厌Mybatis的其中一个原因就是因为这个～

hibernate这种生成SQL是＂运行时＂的；而Mybatis是＂编译时＂的，改动一个字段需要手动＂修改＂或者重新生成XML（这种需求在实际开发当中是很常见的，尤其是系统设计时间比较紧或者一些小项目，开发期间需要变动字段是很普遍的～）

因为Mybatis这种机制，我觉得目前没有很好的办法处理这个问题；

我们之前一般是将＂手写的＂和＂生成的＂分开管理～

修改字段后手写（自己管理的）自己改SQL，自动生成的重新生成一遍（可使用一些自动化工具，脚本，插件之类的）；

个人觉得这种方式根本谈不上优雅（希望有人能真正给一个优雅的方式）～

总之我一直觉得Mybatis多数情况下不是一个很好地选择；

比如一些简单的小项目（比如个人博客这种）可以看看nutz这种框架；企业级管理软件之类的用hibernate（hibernate用代码直接数据库建模，然后导出DDL和文档可以省去很多工作，出来的模型约束和完整性都还不错，该加的约束和索引都能帮你加上，如果你自己设计数据库你还得考虑一遍这部分内容）；银行／支付或者你认为hibernate有问题的项目（一般有问题，是因为你的开发人员hold不住，经验不够，而不是hibernate本身的问题）就用DButils，JDBCTemplate 或者自己封装一个工具；

如果你们公司很大，有专门的人帮你写SQL，检查SQL你再考虑Mybatis～

个人意见～

 

我介绍一下我司是如何做的。

思路如下：统一xml模板，使sql无论增加什么字段，最终的xml文件是一致的，“宛如全新”的一样。

---

<?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="cn.kanmars.sn.dao.TblDemoInfoMapper"><resultMap id="BaseResultMap" type="cn.kanmars.sn.entity.TblDemoInfo"><constructor><idArg column="demo_id" javaType="java.lang.Integer" jdbcType="DECIMAL" /><arg column="demo_nm" javaType="java.lang.String" jdbcType="VARCHAR" /><arg column="demo_money" javaType="java.math.BigDecimal" jdbcType="DECIMAL" /><arg column="create_date" javaType="java.lang.String" jdbcType="CHAR" /><arg column="create_time" javaType="java.lang.String" jdbcType="CHAR" /><arg column="select_static" javaType="java.lang.String" jdbcType="CHAR" /><arg column="select_dynamic" javaType="java.lang.String" jdbcType="CHAR" /><arg column="radio_static" javaType="java.lang.String" jdbcType="CHAR" /><arg column="radio_dynamic" javaType="java.lang.String" jdbcType="CHAR" /><arg column="checkbox_static" javaType="java.lang.String" jdbcType="VARCHAR" /><arg column="checkbox_dynamic" javaType="java.lang.String" jdbcType="VARCHAR" /><arg column="net_address" javaType="java.lang.String" jdbcType="VARCHAR" /><arg column="count_number" javaType="java.lang.Integer" jdbcType="DECIMAL" /></constructor></resultMap><sql id="Base_Column_List">demo_id,demo_nm,demo_money,create_date,create_time,select_static,select_dynamic,radio_static,radio_dynamic,checkbox_static,checkbox_dynamic,net_address,count_number</sql><select id="select" parameterType="cn.kanmars.sn.entity.TblDemoInfo" resultMap="BaseResultMap">select<include refid="Base_Column_List" />from tbl_demo_infowhere 1=1<if test="demoId != null and demoId != '' ">and demo_id = #{demoId,jdbcType=DECIMAL}</if><if test="demoNm != null and demoNm != '' ">and demo_nm = #{demoNm,jdbcType=VARCHAR}</if><if test="demoMoney != null and demoMoney != '' ">and demo_money = #{demoMoney,jdbcType=DECIMAL}</if><if test="createDate != null and createDate != '' ">and create_date = #{createDate,jdbcType=CHAR}</if><if test="createTime != null and createTime != '' ">and create_time = #{createTime,jdbcType=CHAR}</if><if test="selectStatic != null and selectStatic != '' ">and select_static = #{selectStatic,jdbcType=CHAR}</if><if test="selectDynamic != null and selectDynamic != '' ">and select_dynamic = #{selectDynamic,jdbcType=CHAR}</if><if test="radioStatic != null and radioStatic != '' ">and radio_static = #{radioStatic,jdbcType=CHAR}</if><if test="radioDynamic != null and radioDynamic != '' ">and radio_dynamic = #{radioDynamic,jdbcType=CHAR}</if><if test="checkboxStatic != null and checkboxStatic != '' ">and checkbox_static = #{checkboxStatic,jdbcType=VARCHAR}</if><if test="checkboxDynamic != null and checkboxDynamic != '' ">and checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR}</if><if test="netAddress != null and netAddress != '' ">and net_address = #{netAddress,jdbcType=VARCHAR}</if><if test="countNumber != null and countNumber != '' ">and count_number = #{countNumber,jdbcType=DECIMAL}</if></select><select id="selectList" parameterType="cn.kanmars.sn.entity.TblDemoInfo" resultMap="BaseResultMap">select<include refid="Base_Column_List" />from tbl_demo_infowhere 1=1<if test="demoId != null and demoId != '' ">and demo_id = #{demoId,jdbcType=DECIMAL}</if><if test="demoNm != null and demoNm != '' ">and demo_nm = #{demoNm,jdbcType=VARCHAR}</if><if test="demoMoney != null and demoMoney != '' ">and demo_money = #{demoMoney,jdbcType=DECIMAL}</if><if test="createDate != null and createDate != '' ">and create_date = #{createDate,jdbcType=CHAR}</if><if test="createTime != null and createTime != '' ">and create_time = #{createTime,jdbcType=CHAR}</if><if test="selectStatic != null and selectStatic != '' ">and select_static = #{selectStatic,jdbcType=CHAR}</if><if test="selectDynamic != null and selectDynamic != '' ">and select_dynamic = #{selectDynamic,jdbcType=CHAR}</if><if test="radioStatic != null and radioStatic != '' ">and radio_static = #{radioStatic,jdbcType=CHAR}</if><if test="radioDynamic != null and radioDynamic != '' ">and radio_dynamic = #{radioDynamic,jdbcType=CHAR}</if><if test="checkboxStatic != null and checkboxStatic != '' ">and checkbox_static = #{checkboxStatic,jdbcType=VARCHAR}</if><if test="checkboxDynamic != null and checkboxDynamic != '' ">and checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR}</if><if test="netAddress != null and netAddress != '' ">and net_address = #{netAddress,jdbcType=VARCHAR}</if><if test="countNumber != null and countNumber != '' ">and count_number = #{countNumber,jdbcType=DECIMAL}</if></select><insert id="insert" parameterType="cn.kanmars.sn.entity.TblDemoInfo" >insert into tbl_demo_info<trim prefix="(" suffix=")" suffixOverrides=","><if test="demoId != null ">demo_id,</if><if test="demoNm != null ">demo_nm,</if><if test="demoMoney != null ">demo_money,</if><if test="createDate != null ">create_date,</if><if test="createTime != null ">create_time,</if><if test="selectStatic != null ">select_static,</if><if test="selectDynamic != null ">select_dynamic,</if><if test="radioStatic != null ">radio_static,</if><if test="radioDynamic != null ">radio_dynamic,</if><if test="checkboxStatic != null ">checkbox_static,</if><if test="checkboxDynamic != null ">checkbox_dynamic,</if><if test="netAddress != null ">net_address,</if><if test="countNumber != null ">count_number,</if></trim><trim prefix="values (" suffix=")" suffixOverrides=","><if test="demoId != null ">#{demoId,jdbcType=DECIMAL},</if><if test="demoNm != null ">#{demoNm,jdbcType=VARCHAR},</if><if test="demoMoney != null ">#{demoMoney,jdbcType=DECIMAL},</if><if test="createDate != null ">#{createDate,jdbcType=CHAR},</if><if test="createTime != null ">#{createTime,jdbcType=CHAR},</if><if test="selectStatic != null ">#{selectStatic,jdbcType=CHAR},</if><if test="selectDynamic != null ">#{selectDynamic,jdbcType=CHAR},</if><if test="radioStatic != null ">#{radioStatic,jdbcType=CHAR},</if><if test="radioDynamic != null ">#{radioDynamic,jdbcType=CHAR},</if><if test="checkboxStatic != null ">#{checkboxStatic,jdbcType=VARCHAR},</if><if test="checkboxDynamic != null ">#{checkboxDynamic,jdbcType=VARCHAR},</if><if test="netAddress != null ">#{netAddress,jdbcType=VARCHAR},</if><if test="countNumber != null ">#{countNumber,jdbcType=DECIMAL},</if></trim></insert><update id="updateByPrimaryKey" parameterType="cn.kanmars.sn.entity.TblDemoInfo" >update tbl_demo_info<set><if test="demoNm != null">demo_nm = #{demoNm,jdbcType=VARCHAR} ,</if><if test="demoMoney != null">demo_money = #{demoMoney,jdbcType=DECIMAL} ,</if><if test="createDate != null">create_date = #{createDate,jdbcType=CHAR} ,</if><if test="createTime != null">create_time = #{createTime,jdbcType=CHAR} ,</if><if test="selectStatic != null">select_static = #{selectStatic,jdbcType=CHAR} ,</if><if test="selectDynamic != null">select_dynamic = #{selectDynamic,jdbcType=CHAR} ,</if><if test="radioStatic != null">radio_static = #{radioStatic,jdbcType=CHAR} ,</if><if test="radioDynamic != null">radio_dynamic = #{radioDynamic,jdbcType=CHAR} ,</if><if test="checkboxStatic != null">checkbox_static = #{checkboxStatic,jdbcType=VARCHAR} ,</if><if test="checkboxDynamic != null">checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR} ,</if><if test="netAddress != null">net_address = #{netAddress,jdbcType=VARCHAR} ,</if><if test="countNumber != null">count_number = #{countNumber,jdbcType=DECIMAL} ,</if></set>where 1=1and demo_id = #{demoId,jdbcType=DECIMAL}</update><delete id="delete" parameterType="cn.kanmars.sn.entity.TblDemoInfo" >delete from tbl_demo_infowhere 1=1<if test="demoId != null and demoId != '' ">and demo_id = #{demoId,jdbcType=DECIMAL}</if><if test="demoNm != null and demoNm != '' ">and demo_nm = #{demoNm,jdbcType=VARCHAR}</if><if test="demoMoney != null and demoMoney != '' ">and demo_money = #{demoMoney,jdbcType=DECIMAL}</if><if test="createDate != null and createDate != '' ">and create_date = #{createDate,jdbcType=CHAR}</if><if test="createTime != null and createTime != '' ">and create_time = #{createTime,jdbcType=CHAR}</if><if test="selectStatic != null and selectStatic != '' ">and select_static = #{selectStatic,jdbcType=CHAR}</if><if test="selectDynamic != null and selectDynamic != '' ">and select_dynamic = #{selectDynamic,jdbcType=CHAR}</if><if test="radioStatic != null and radioStatic != '' ">and radio_static = #{radioStatic,jdbcType=CHAR}</if><if test="radioDynamic != null and radioDynamic != '' ">and radio_dynamic = #{radioDynamic,jdbcType=CHAR}</if><if test="checkboxStatic != null and checkboxStatic != '' ">and checkbox_static = #{checkboxStatic,jdbcType=VARCHAR}</if><if test="checkboxDynamic != null and checkboxDynamic != '' ">and checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR}</if><if test="netAddress != null and netAddress != '' ">and net_address = #{netAddress,jdbcType=VARCHAR}</if><if test="countNumber != null and countNumber != '' ">and count_number = #{countNumber,jdbcType=DECIMAL}</if></delete><select id="queryOneMap" parameterType="java.util.HashMap" resultType="java.util.HashMap">select<include refid="Base_Column_List" />from tbl_demo_infowhere 1=1<if test="demoId != null and demoId != '' ">and demo_id = #{demoId,jdbcType=DECIMAL}</if><if test="demoNm != null and demoNm != '' ">and demo_nm = #{demoNm,jdbcType=VARCHAR}</if><if test="demoMoney != null and demoMoney != '' ">and demo_money = #{demoMoney,jdbcType=DECIMAL}</if><if test="createDate != null and createDate != '' ">and create_date = #{createDate,jdbcType=CHAR}</if><if test="createTime != null and createTime != '' ">and create_time = #{createTime,jdbcType=CHAR}</if><if test="selectStatic != null and selectStatic != '' ">and select_static = #{selectStatic,jdbcType=CHAR}</if><if test="selectDynamic != null and selectDynamic != '' ">and select_dynamic = #{selectDynamic,jdbcType=CHAR}</if><if test="radioStatic != null and radioStatic != '' ">and radio_static = #{radioStatic,jdbcType=CHAR}</if><if test="radioDynamic != null and radioDynamic != '' ">and radio_dynamic = #{radioDynamic,jdbcType=CHAR}</if><if test="checkboxStatic != null and checkboxStatic != '' ">and checkbox_static = #{checkboxStatic,jdbcType=VARCHAR}</if><if test="checkboxDynamic != null and checkboxDynamic != '' ">and checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR}</if><if test="netAddress != null and netAddress != '' ">and net_address = #{netAddress,jdbcType=VARCHAR}</if><if test="countNumber != null and countNumber != '' ">and count_number = #{countNumber,jdbcType=DECIMAL}</if></select><select id="queryListMap" parameterType="java.util.HashMap" resultType="java.util.HashMap">select<include refid="Base_Column_List" />from tbl_demo_infowhere 1=1<if test="demoId != null and demoId != '' ">and demo_id = #{demoId,jdbcType=DECIMAL}</if><if test="demoNm != null and demoNm != '' ">and demo_nm = #{demoNm,jdbcType=VARCHAR}</if><if test="demoMoney != null and demoMoney != '' ">and demo_money = #{demoMoney,jdbcType=DECIMAL}</if><if test="createDate != null and createDate != '' ">and create_date = #{createDate,jdbcType=CHAR}</if><if test="createTime != null and createTime != '' ">and create_time = #{createTime,jdbcType=CHAR}</if><if test="selectStatic != null and selectStatic != '' ">and select_static = #{selectStatic,jdbcType=CHAR}</if><if test="selectDynamic != null and selectDynamic != '' ">and select_dynamic = #{selectDynamic,jdbcType=CHAR}</if><if test="radioStatic != null and radioStatic != '' ">and radio_static = #{radioStatic,jdbcType=CHAR}</if><if test="radioDynamic != null and radioDynamic != '' ">and radio_dynamic = #{radioDynamic,jdbcType=CHAR}</if><if test="checkboxStatic != null and checkboxStatic != '' ">and checkbox_static = #{checkboxStatic,jdbcType=VARCHAR}</if><if test="checkboxDynamic != null and checkboxDynamic != '' ">and checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR}</if><if test="netAddress != null and netAddress != '' ">and net_address = #{netAddress,jdbcType=VARCHAR}</if><if test="countNumber != null and countNumber != '' ">and count_number = #{countNumber,jdbcType=DECIMAL}</if></select><update id="updateCAS" parameterType="java.util.HashMap" >update tbl_demo_info<set><if test="demoNm_new != null">demo_nm = #{demoNm_new,jdbcType=VARCHAR} ,</if><if test="demoMoney_new != null">demo_money = #{demoMoney_new,jdbcType=DECIMAL} ,</if><if test="createDate_new != null">create_date = #{createDate_new,jdbcType=CHAR} ,</if><if test="createTime_new != null">create_time = #{createTime_new,jdbcType=CHAR} ,</if><if test="selectStatic_new != null">select_static = #{selectStatic_new,jdbcType=CHAR} ,</if><if test="selectDynamic_new != null">select_dynamic = #{selectDynamic_new,jdbcType=CHAR} ,</if><if test="radioStatic_new != null">radio_static = #{radioStatic_new,jdbcType=CHAR} ,</if><if test="radioDynamic_new != null">radio_dynamic = #{radioDynamic_new,jdbcType=CHAR} ,</if><if test="checkboxStatic_new != null">checkbox_static = #{checkboxStatic_new,jdbcType=VARCHAR} ,</if><if test="checkboxDynamic_new != null">checkbox_dynamic = #{checkboxDynamic_new,jdbcType=VARCHAR} ,</if><if test="netAddress_new != null">net_address = #{netAddress_new,jdbcType=VARCHAR} ,</if><if test="countNumber_new != null">count_number = #{countNumber_new,jdbcType=DECIMAL} ,</if></set>where 1=1<if test="demoId != null ">and demo_id = #{demoId,jdbcType=DECIMAL}</if><if test="demoNm != null ">and demo_nm = #{demoNm,jdbcType=VARCHAR}</if><if test="demoMoney != null ">and demo_money = #{demoMoney,jdbcType=DECIMAL}</if><if test="createDate != null ">and create_date = #{createDate,jdbcType=CHAR}</if><if test="createTime != null ">and create_time = #{createTime,jdbcType=CHAR}</if><if test="selectStatic != null ">and select_static = #{selectStatic,jdbcType=CHAR}</if><if test="selectDynamic != null ">and select_dynamic = #{selectDynamic,jdbcType=CHAR}</if><if test="radioStatic != null ">and radio_static = #{radioStatic,jdbcType=CHAR}</if><if test="radioDynamic != null ">and radio_dynamic = #{radioDynamic,jdbcType=CHAR}</if><if test="checkboxStatic != null ">and checkbox_static = #{checkboxStatic,jdbcType=VARCHAR}</if><if test="checkboxDynamic != null ">and checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR}</if><if test="netAddress != null ">and net_address = #{netAddress,jdbcType=VARCHAR}</if><if test="countNumber != null ">and count_number = #{countNumber,jdbcType=DECIMAL}</if></update><select id="queryForPage" parameterType="java.util.HashMap" resultType="java.util.HashMap"><if test="countFlag != null and countFlag == 'Y'.toString() ">select count(1) as TOTALCOUNT from (</if>select<include refid="Base_Column_List" />from tbl_demo_infowhere 1=1<if test="demoId != null and demoId != '' ">and demo_id = #{demoId,jdbcType=DECIMAL}</if><if test="demoNm != null and demoNm != '' ">and demo_nm like CONCAT(#{demoNm,jdbcType=VARCHAR},'%')</if><if test="demoMoney != null and demoMoney != '' ">and demo_money = #{demoMoney,jdbcType=DECIMAL}</if><if test="createDate != null and createDate != '' ">and create_date = #{createDate,jdbcType=CHAR}</if><if test="createDate_start != null and createDate_start != '' ">and create_date &gt;= #{createDate_start,jdbcType=CHAR}</if><if test="createDate_end != null and createDate_end != '' ">and create_date &lt;= #{createDate_end,jdbcType=CHAR}</if><if test="createTime != null and createTime != '' ">and create_time = #{createTime,jdbcType=CHAR}</if><if test="selectStatic != null and selectStatic != '' ">and select_static = #{selectStatic,jdbcType=CHAR}</if><if test="selectDynamic != null and selectDynamic != '' ">and select_dynamic = #{selectDynamic,jdbcType=CHAR}</if><if test="radioStatic != null and radioStatic != '' ">and radio_static = #{radioStatic,jdbcType=CHAR}</if><if test="radioDynamic != null and radioDynamic != '' ">and radio_dynamic = #{radioDynamic,jdbcType=CHAR}</if><if test="checkboxStatic != null and checkboxStatic != '' ">and checkbox_static = #{checkboxStatic,jdbcType=VARCHAR}</if><if test="checkboxDynamic != null and checkboxDynamic != '' ">and checkbox_dynamic = #{checkboxDynamic,jdbcType=VARCHAR}</if><if test="netAddress != null and netAddress != '' ">and net_address like CONCAT(#{netAddress,jdbcType=VARCHAR},'%')</if><if test="countNumber != null and countNumber != '' ">and count_number = #{countNumber,jdbcType=DECIMAL}</if><if test="countFlag != null and countFlag == 'N'.toString() ">limit #{limitStart,jdbcType=DECIMAL},#{limitSize,jdbcType=DECIMAL}</if><if test="countFlag != null and countFlag == 'Y'.toString() ">) as TMP_COUNT_TABLE</if></select><!-- 如果是mysql数据库，需要在jdbcUrl中设置allowMultiQueries=true参数才可以使用 --><!-- 返回值为第一条更新语句的执行结果，并非所有批量更新的语句总和 --><!--ORACLE的写法<insert id="insertBatch"  parameterType="java.util.List"><foreach collection="list" item="item" index="index" open="begin" close="end;" separator=";">insert into test (a,b,c) values (#{item.a},#{item.b},#{item.c})</foreach></insert>MYSQL的写法<insert id="insertBatch"  parameterType="java.util.List">insert into test (a,b,c) values <foreach collection="list" item="item" index="index" open="(" close=")" separator=",">#{item.a},#{item.b},#{item.c}</foreach></insert>--><insert id="insertBatch"  parameterType="java.util.List">insert into tbl_demo_info (demo_id,demo_nm,demo_money,create_date,create_time,select_static,select_dynamic,radio_static,radio_dynamic,checkbox_static,checkbox_dynamic,net_address,count_number) values <foreach collection="list" item="item" index="index" open="(" close=")" separator="),(">#{item.demoId},#{item.demoNm},#{item.demoMoney},#{item.createDate},#{item.createTime},#{item.selectStatic},#{item.selectDynamic},#{item.radioStatic},#{item.radioDynamic},#{item.checkboxStatic},#{item.checkboxDynamic},#{item.netAddress},#{item.countNumber}</foreach></insert><!-- 如果是mysql数据库，需要在jdbcUrl中设置allowMultiQueries=true参数才可以使用 --><!-- 返回值为第一条更新语句的执行结果，并非所有批量更新的语句总和 --><!--ORACLE的写法<update id="updateBatch"  parameterType="java.util.List"><foreach collection="list" item="item" index="index" open="begin" close="end;" separator=";">update test<set>test=${item.test}+1</set>where id = ${item.id}</foreach></update>MYSQL的写法<update id="updateBatch"  parameterType="java.util.List"><foreach collection="list" item="item" index="index" open="" close="" separator=";">update test<set>test=${item.test}+1</set>where id = ${item.id}</foreach></update>--><update id="updateBatch" parameterType="java.util.List" ><foreach collection="list" item="item" index="index" open="" close="" separator=";">update tbl_demo_info<set><if test="item.demoNm_new != null">demo_nm = #{item.demoNm_new,jdbcType=VARCHAR} ,</if><if test="item.demoMoney_new != null">demo_money = #{item.demoMoney_new,jdbcType=DECIMAL} ,</if><if test="item.createDate_new != null">create_date = #{item.createDate_new,jdbcType=CHAR} ,</if><if test="item.createTime_new != null">create_time = #{item.createTime_new,jdbcType=CHAR} ,</if><if test="item.selectStatic_new != null">select_static = #{item.selectStatic_new,jdbcType=CHAR} ,</if><if test="item.selectDynamic_new != null">select_dynamic = #{item.selectDynamic_new,jdbcType=CHAR} ,</if><if test="item.radioStatic_new != null">radio_static = #{item.radioStatic_new,jdbcType=CHAR} ,</if><if test="item.radioDynamic_new != null">radio_dynamic = #{item.radioDynamic_new,jdbcType=CHAR} ,</if><if test="item.checkboxStatic_new != null">checkbox_static = #{item.checkboxStatic_new,jdbcType=VARCHAR} ,</if><if test="item.checkboxDynamic_new != null">checkbox_dynamic = #{item.checkboxDynamic_new,jdbcType=VARCHAR} ,</if><if test="item.netAddress_new != null">net_address = #{item.netAddress_new,jdbcType=VARCHAR} ,</if><if test="item.countNumber_new != null">count_number = #{item.countNumber_new,jdbcType=DECIMAL} ,</if></set>where 1=1<if test="item.demoId != null ">and demo_id = #{item.demoId,jdbcType=DECIMAL}</if><if test="item.demoNm != null ">and demo_nm = #{item.demoNm,jdbcType=VARCHAR}</if><if test="item.demoMoney != null ">and demo_money = #{item.demoMoney,jdbcType=DECIMAL}</if><if test="item.createDate != null ">and create_date = #{item.createDate,jdbcType=CHAR}</if><if test="item.createTime != null ">and create_time = #{item.createTime,jdbcType=CHAR}</if><if test="item.selectStatic != null ">and select_static = #{item.selectStatic,jdbcType=CHAR}</if><if test="item.selectDynamic != null ">and select_dynamic = #{item.selectDynamic,jdbcType=CHAR}</if><if test="item.radioStatic != null ">and radio_static = #{item.radioStatic,jdbcType=CHAR}</if><if test="item.radioDynamic != null ">and radio_dynamic = #{item.radioDynamic,jdbcType=CHAR}</if><if test="item.checkboxStatic != null ">and checkbox_static = #{item.checkboxStatic,jdbcType=VARCHAR}</if><if test="item.checkboxDynamic != null ">and checkbox_dynamic = #{item.checkboxDynamic,jdbcType=VARCHAR}</if><if test="item.netAddress != null ">and net_address = #{item.netAddress,jdbcType=VARCHAR}</if><if test="item.countNumber != null ">and count_number = #{item.countNumber,jdbcType=DECIMAL}</if></foreach></update><select id="selectByPrimaryKey" resultMap="BaseResultMap">select<include refid="Base_Column_List" />from tbl_demo_infowhere 1=1and demo_id = #{0}</select>
</mapper>

按照以上模板，

增加字段，只需要在指定的几个位置修改即可：共计15个位置。且这几个位置都是可以通过正则表达式匹配出来的，可以“工具化”的在某个字段后新增字段。

再说一下我司的ORM层设计，mybatis有官方的mybatisgenerator，但是实际工作中不太好用，因此我们自己开发了一套mybatismapper生成工具，按照类似上面的xml的格式：

1、生成xml文件。

2、xml文件中固定有：select查询对象、selectList查询对象列表、insert插入对象、updateByPrimaryKey根据主键修改对象、delete删除对象、queryOneMap查询Map、queryListMap查询Map列表、updateCAS原子性更新、queryForPage分页查询、insertBatch批量插入、updateBatch批量更新、selectByPrimaryKey主键查询 共十二种标准SQL语句，覆盖了绝大多数场景。

3、xml中的和字段相关的行全部独立为一行，方便新增字段时全局替换，或者beyoundcompare对比，或者svnmerge，或者gitmerge

4、开发了工具包，针对xml文件，输入字段和自动类型，自动找到指定位置新增字段

5、开发了工具包，针对xml文件，实现了mysql->oracle->db2->sqlite->sqlserver五种数据库的相互转换

6、开发了工具包，针对整体的数据库层，设计了“页面元素描述语言”，根据DB中的comment，或者参数型的设计，全套自动生成：mapper.java,mapper.xml,entity,logic,controller,ftl,js,页面校验，页面排版，一整套都是自动生成的。

可以说，我司的后台开发人员，仅需安装powerdesign软件，然后用各种自动化工具，就能把整套系统完成到可上线状态。

而题主所说的“包含了手写的部分联合查询”，在这套方案里，不过是queryForPage分页查询的SQL语句不同罢了，我一般喜欢beyoundcompare一下，然后把旧的queryForPage放到新的xml上，提交SVN即可。

对于实体类，只能手动加。

xml可以用sql标签将字段写到一处。

看看是否可以添加到新表，写新的实体对象。不用在原表上添加。