＜trim prefix=““ suffix=““ suffixOverrides=““ prefixOverrides=““＞
＜/trim＞

prefix:在trim标签内sql语句加上前缀

suffix:在trim标签内sql语句加上后缀

suffixOverrides:指定去除多余的后缀内容，如：suffixOverrides=","，去除trim标签内sql语句多余的后缀","

prefixOverrides:指定去除多余的前缀内容

<insert id="方法名" parameterType="" useGeneratedKeys="" keyProperty="" >
    insert into 表名
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="a != null" >
        a ,
      </if>
      ...........
      
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >

      <if test="a != null" >
        #{a},
      </if>
     ............

    </trim>
    <selectKey resultType="" order="" keyProperty="">
      ......
    </selectKey>
</insert>

useGeneratedKeys=""

keyProperty=""