Mybatis動態SQL trim

<insert id="insertSelective" parameterType="com.geo.entity.SysUser">
    insert into sys_user
    <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="id != null">
        id,
      </if>
      <if test="userName != null">
        user_name,
      </if>
      <if test="userPassword != null">
        user_password,
      </if>
      <if test="userEmail != null">
        user_email,
      </if>
      <if test="userInfo != null">
        user_info,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
      <if test="id != null">
        #{id,jdbcType=INTEGER},
      </if>
      <if test="userName != null">
        #{userName,jdbcType=VARCHAR},
      </if>
      <if test="userPassword != null">
        #{userPassword,jdbcType=VARCHAR},
      </if>
      <if test="userEmail != null">
        #{userEmail,jdbcType=VARCHAR},
      </if>
      <if test="userInfo != null">
        #{userInfo,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>

trim 標籤有四個屬性：
prefix: 增加的前綴
prefixOverrides:刪除指定的前綴
suffix:增加指定後綴
suffixOverrides:刪除指定後綴

where標籤，和set標籤都是通過trim標籤實現的!