1.查找表中單個字段的值有哪些相同的記錄:
假設表名是table，列名是column，則查詢語句為：
SELECT * FROM table WHERE column IN (SELECT column FROM table GROUP BY column HAVING COUNT(column)>1)
2.查找表中多個字段的值有哪些相同的記錄:
假設表名是table，列名是column1,列名column2,則查詢語句為：
SELECT A.* FROM table A RIGHT JOIN (SELECT column1,column2 FROM table group by column1,column2 HAVING COUNT(*)>1 ) B ON A.column1 = B.cloumn1 AND A.column2 = B.column2
先查找出字段1,字段2的值相同的記錄,別名B,再通過右連接,找出字段1,字段2中相同的數據.