nested exception is java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax

今天进行查询的时候，遇到此错误

nested exception is java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ’

GROUP BY
    pay_time,
    pay_type_code,
    park_name' at line 13

网上查询很多说是 语句中使用了mysql关键字，

SELECT
   DATE_FORMAT( pay_order.pay_time, '%Y%m%d' ) AS pay_time,
   pay_order.pay_type_code AS pay_type_code,
   park.NAME AS park_name
FROM
   `pay_order`
LEFT JOIN park_order ON pay_order.trade_pay_no = park_order.id
LEFT JOIN park ON park_order.park_id = park.id
WHERE
   pay_order.STATUS = 2
   <if test="trandate !=null and trandate!=''">and DATE_FORMAT(pay_order.pay_time,'%Y%m%d') = #{trandate}</if>
   <if test="parkName !=null and parkName!=''">and park.name = #{parkName}</if>
   <if test="payType !=null and payType!=''">and pay_order.pay_type_code = #{payType};</if>
GROUP BY
   pay_time,
   pay_type_code,
   park_name

但是这个sql在Navicat中可以执行，后来才发现在group by 关键字前面，也就是最后一个if的后面，多加了一个逗号“,”

遇到这种问题一定要仔细检查sql