mybatis if test 不为空字符串或null

  	
        and  a.product_id = #{productId,jdbcType=VARCHAR}
      
      
        and a.product_defin_id = #{productDefinId,jdbcType=VARCHAR}
      
      
        and a.product_uid = #{productUid,jdbcType=VARCHAR}
      
      
        and a.product_key = #{productKey,jdbcType=VARCHAR}
      
      
        and a.prouuct_secret = #{prouuctSecret,jdbcType=VARCHAR}
      
      
        and a.product_pass = #{productPass,jdbcType=VARCHAR}
      
      
        and a.product_visit_pass = #{productVisitPass,jdbcType=VARCHAR}
      
      
        and a.create_time = #{createTime,jdbcType=VARCHAR}
      
            
         ORDER BY a.product_id DESC limit #{pageNum},#{pageSize}