mysql 用union以后再用limit，查询的字段影响数据结果？

SQL1以下：

SELECT count(*) FROM 
( SELECT id,product title, images,type , '冻品加工' categoryName, create_time createTime FROM sad_technology 
UNION SELECT id,CONCAT(start_city,'-',end_city) title, images,type ,'冷链物流' categoryName, create_time createTime FROM sad_transport 
UNION SELECT id,title, images, type,'冷链仓储' categoryName, create_time createTime FROM sad_warehouse_emand 
UNION SELECT id,product_name title, images, type,'冻品交易' categoryName, create_time createTime FROM sad_transaction 
) t 
WHERE t.type = 'SUPPLY' order by t.createTime desc

结果以下：结果有83条记录

执行SQL2,结果有73条记录

SELECT count(*) FROM ( 
SELECT product title, images,type , '冻品加工' categoryName, create_time createTime FROM sad_technology 
UNION SELECT CONCAT(start_city,'-',end_city) title, images,type ,'冷链物流' categoryName, create_time createTime FROM sad_transport 
UNION SELECT title, images, type,'冷链仓储' categoryName, create_time createTime FROM sad_warehouse_emand 
UNION SELECT product_name title, images, type,'冻品交易' categoryName, create_time createTime FROM sad_transaction ) 
t WHERE t.type = 'SUPPLY' ORDER BY createTime

很奇怪。仔细分析sql1和sql2的区别是sql1里子查询里边每一个表查询多了个id字段

已知id为每一个表的主键且在每一个表中都惟一且不为空.结果为啥不同嘞？

再补充两张数据图吧： 没id的sql
有id的sql

此时数据库里又多了几天记录。有order by的缘由是须要排序后limit数据。