mybatis中的几个注意的地方

Posted 2020-10-13

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>

3.<trim prefix="" suffix="" suffixOverrides="" prefixOverrides="">

  <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>

　　

</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