sql片段，解决重复sql字段输入
where：添加where，去除第一个and
set：添加set，去除第一个，号
<?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"> <!-- namespace:表示名称空间。现在的目的是区分id的. --> <mapper namespace="com.zhiyou100.xf.dao.UsersDao"> <!-- 根据id查询用户。id:标识该标签。 parameterType:参数类型。可以写 也可以省略 resultType:返回结果的类型。 #{id}:类似于EL表达式。 解析id的值 --> <sql id="content"> id,name,age,sex,address </sql> <select id="selAll" resultType="com.zhiyou100.xf.bean.Users"> select <include refid="content"></include> from users </select> <select id="getUser" parameterType="com.zhiyou100.xf.bean.Users" resultType="com.zhiyou100.xf.bean.Users"> select <include refid="content"></include> from users where <if test="id!=null"> id=#{id} </if> <if test="age!=null"> and age=#{age} </if> </select> <select id="getWhere" parameterType="com.zhiyou100.xf.bean.Users" resultType="com.zhiyou100.xf.bean.Users"> select <include refid="content"></include> from users <where> <if test="id!=null"> id=#{id} </if> <if test="age!=null"> and age=#{age} </if> </where> </select> <update id="update" parameterType="com.zhiyou100.xf.bean.Users"> update Users <set> <if test="id!=null"> name=#{name}, </if> <if test="age!=null"> age=#{age} </if> </set> where id=#{id} </update> <select id="sel1" parameterType="com.zhiyou100.xf.bean.Users" resultType="com.zhiyou100.xf.bean.Users"> select <include refid="content"></include> from users <where> <choose> <when test="id!=null"> id=#{id} </when> <when test="age!=null"> age=#{age} </when> </choose> </where> </select> <select id="sel2" parameterType="com.zhiyou100.xf.bean.Users" resultType="com.zhiyou100.xf.bean.Users"> select <include refid="content"></include> from users <trim prefix="where" prefixOverrides="and"> <if test="id!=null"> id=#{id} </if> <if test="age!=null"> and age=#{age} </if> </trim> </select> <update id="update2" parameterType="com.zhiyou100.xf.bean.Users"> update Users <trim prefix="set" suffixOverrides=","> <if test="age!=null"> age=#{age}, </if> <if test="name!=null"> name=#{name}, </if> </trim> where id=#{id} </update> <select id="sellByIds" resultType="com.zhiyou100.xf.bean.Users"> select * from Users <where> <foreach collection="list" item="id" separator="or"> id=#{id} </foreach> </where> </select> <select id="sellIn" resultType="com.zhiyou100.xf.bean.Users"> select * from Users <where> <foreach collection="list" open="id in(" close=")" item="id" separator=","> #{id} </foreach> </where> </select> </mapper>
来源：博客园
作者：啊呜啊
链接：https://www.cnblogs.com/accc111/p/11449119.html