Mybatis的xml配置备忘

       <!-- 利用hashmap传递参数数据查询用户 -->
       <select id ="selectUserById4Map" parameterType="string" resultType="hashmap" >
            select
                   <include refid ="allColumns" />
                from user where id = #{id}
       </select>
      
       <!-- 利用hashmap传递参数数据插入用户信息 -->
       <select id ="insertUser4Map" parameterType="hashmap" >
            insert into user(id,name,age,address) values(#{id},#{name},#{age},#{address})
       </select>
      
       <!-- 模糊查询 -->
       <select id ="selectUserByCondition3" parameterType="com.judy.mybatis.domain.User" resultType="com.judy.mybatis.domain.User" >
            select * from user where 1 = 1
             <if test ="id!=null" >
                  and id = #{id}
             </if>
             <if test ="name!=null" >
                  and name like ‘%${name}%‘
             </if>
             <if test ="age!=null" >
                  and age = #{age}
             </if>
             <if test ="address!=null" >
                  and address = #{address}
             </if>
       </select>

 <!-- 利用动态sql语句更新user数据 -->
       <insert id ="updateUserByCondition" parameterType="com.judy.mybatis.domain.User" >
            update user
                   <set>
                         <if test ="name!=null" >
                              name = #{name}
                         </if>
                         <if test ="age!=null" >
                              age = #{age}
                         </if>
                         <if test ="address!=null" >
                              address = #{address}
                         </if>
                   </set>
            where id=#{id}
       </insert>
      
       <!-- 动态seql语句查询用户 -->
       <select id ="selectUserByCondition" parameterType="com.judy.mybatis.domain.User" resultType="com.judy.mybatis.domain.User" >
            select * from user where 1 = 1
             <if test ="id!=null" >
                  and id = #{id}
             </if>
             <if test ="name!=null" >
                  and name = #{name}
             </if>
             <if test ="age!=null" >
                  and age = #{age}
             </if>
             <if test ="address!=null" >
                  and address = #{address}
             </if>
       </select>
      
       <!-- 动态seql语句查询用户方式2 -->
       <!-- 这种方式会自动根据是否有id，如果有没有id，那么第一个条件将不加and -->
       <select id ="selectUserByCondition2" parameterType="com.judy.mybatis.domain.User" resultType="com.judy.mybatis.domain.User" >
            select * from user
             <where>
                   <if test ="id!=null" >
                        id = #{id}
                   </if>
                   <if test ="name!=null" >
                        and name = #{name}
                   </if>
                   <if test ="age!=null" >
                        and age = #{age}
                   </if>
                   <if test ="address!=null" >
                        and address = #{address}
                   </if>
             </where>
       </select>

  <!-- 当字段很多的时候，可以通过下面这种方式抽取字段 -->
       <sql id ="allColumns" >
            id,name,age,address
       </sql>
      
       <!-- 如果在sqlMapConfig.xml中配置了别名，那么这里的resultType就可以直接写User -->
       <select id ="selectUserById" parameterType="string" resultMap="userMap" >
            select
                   <include refid ="allColumns" />
                from user where id = #{id}
       </select>