将#修改为$，即可正常返回

src/main/resources/mapper/szwh/OrderMapper.xml

@@ -99,7 +99,7 @@
 
     <!-- 统计平台在某时间内的订单总额 -->
     <select id="sumOderDtZone" parameterType="java.lang.String" resultType="java.math.BigDecimal">
-        SELECT SUM(#{field})
+        SELECT COALESCE(SUM(${field}),0)
         FROM `order`
         WHERE pay_status=2
         AND (paymenttime BETWEEN CAST(#{startdt} AS DATE) AND CAST(#{enddt} AS DATE))