mysql 用union以後再用limit，查詢的字段影響數據結果？

SQL1以下：

SELECT count(*) FROM 
( SELECT id,product title, images,type , '凍品加工' categoryName, create_time createTime FROM sad_technology 
UNION SELECT id,CONCAT(start_city,'-',end_city) title, images,type ,'冷鏈物流' categoryName, create_time createTime FROM sad_transport 
UNION SELECT id,title, images, type,'冷鏈倉儲' categoryName, create_time createTime FROM sad_warehouse_emand 
UNION SELECT id,product_name title, images, type,'凍品交易' categoryName, create_time createTime FROM sad_transaction 
) t 
WHERE t.type = 'SUPPLY' order by t.createTime desc

結果以下：結果有83條記錄

執行SQL2,結果有73條記錄

SELECT count(*) FROM ( 
SELECT product title, images,type , '凍品加工' categoryName, create_time createTime FROM sad_technology 
UNION SELECT CONCAT(start_city,'-',end_city) title, images,type ,'冷鏈物流' categoryName, create_time createTime FROM sad_transport 
UNION SELECT title, images, type,'冷鏈倉儲' categoryName, create_time createTime FROM sad_warehouse_emand 
UNION SELECT product_name title, images, type,'凍品交易' categoryName, create_time createTime FROM sad_transaction ) 
t WHERE t.type = 'SUPPLY' ORDER BY createTime

很奇怪。仔細分析sql1和sql2的區別是sql1裏子查詢裏邊每一個表查詢多了個id字段

已知id爲每一個表的主鍵且在每一個表中都惟一且不爲空.結果爲啥不同嘞？

再補充兩張數據圖吧： 沒id的sql
有id的sql

此時數據庫裏又多了幾天記錄。有order by的緣由是須要排序後limit數據。