mysql導資料庫用到的語句

將欄位格式為2013-08-09 13:22:55轉換為時間戳

UPDATE `AttendClass` SET `regdate` = unix_timestamp(regDate2) WHERE `rowid` = 118280;

 

將欄位name前面新增一個字元x

update aa set name=concat('x',name)

 

MYSQL查詢重複記錄的方法

1、查詢表中多餘的重複記錄，重複記錄是根據單個欄位（peopleId）來判斷

select * from people   where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1) 

 2、刪除表中多餘的重複記錄，重複記錄是根據單個欄位（peopleId）來判斷，只留有rowid最小的記錄

delete from people   
where peopleId in (select peopleId from people group by peopleId   having count(peopleId) > 1)   
and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1)

 3、查詢表中多餘的重複記錄（多個欄位）

select * from vitae a   
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

 4、刪除表中多餘的重複記錄（多個欄位），只留有rowid最小的記錄

delete from vitae a   
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)   
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

 5、查詢表中多餘的重複記錄（多個欄位），不包含rowid最小的記錄

select * from vitae a   
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)   
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)