1、首先定义一个sql标签，一定要定义唯一id<sql id="Base_Column_List" >name,age</sql>
2、然后通过id引用
<select id="selectAll">
select
<include refid="Base_Column_List" />
from student
</select>
这个<include refid="Base_Column_List" />会自动把上面的代码贴过来。
<trim prefix="(" suffix=")" suffixOverrides="," >
</trim>
<insert id="insertSelective" parameterType="com.dearbinge.data.pojo.Security" >
<!--
WARNING - @mbggenerated
This element is automatically generated by MyBatis Generator, do not modify.
-->
insert into t_security
<trim prefix="(" suffix=")" suffixOverrides="," >
<if test="fSecuritykey != null" >
f_SecurityKey,
</if>
<if test="fSecurityvalue != null" >
f_SecurityValue,
</if>
<if test="fMerchantid != null" >
f_MerchantId,
</if>
<if test="fTag != null" >
f_Tag,
</if>
<if test="fIsdelete != null" >
f_IsDelete,
</if>
<if test="fCreateuser != null" >
f_CreateUser,
</if>
<if test="fCreatetime != null" >
f_CreateTime,
</if>
<if test="fUpdateuser != null" >
f_UpdateUser,
</if>
<if test="fUpdatetime != null" >
f_UpdateTime,
</if>
<if test="fRemark != null" >
f_Remark,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides="," >
<if test="fSecuritykey != null" >
#{fSecuritykey,jdbcType=VARCHAR},
</if>
<if test="fSecurityvalue != null" >
#{fSecurityvalue,jdbcType=VARCHAR},
</if>
<if test="fMerchantid != null" >
#{fMerchantid,jdbcType=VARCHAR},
</if>
<if test="fTag != null" >
#{fTag,jdbcType=VARCHAR},
</if>
<if test="fIsdelete != null" >
#{fIsdelete,jdbcType=INTEGER},
</if>
<if test="fCreateuser != null" >
#{fCreateuser,jdbcType=VARCHAR},
</if>
<if test="fCreatetime != null" >
#{fCreatetime,jdbcType=DATE},
</if>
<if test="fUpdateuser != null" >
#{fUpdateuser,jdbcType=VARCHAR},
</if>
<if test="fUpdatetime != null" >
#{fUpdatetime,jdbcType=DATE},
</if>
<if test="fRemark != null" >
#{fRemark,jdbcType=VARCHAR},
</if>
</trim>
</insert>
原文：http://www.cnblogs.com/zique/p/7786838.html