sp_help table_name --查询表详细信息sql server
desc tables table_name
删除重复数据:
1、oracle 中
delete borrowRecord
--删除表名
where studentId in( --删除重复数据
select studentId from borrowRecord group by studentId having count(studentId)>1
)
and rowid not in( --保留重复数据中的一条数据
select min(rowid) from borrowRecord group by studentId having count(studentId)>1
)
2、SQL server中
delete BorrowRecord
--BorrowRecord 表名
where studentId in(
select studentId from borrowRecord group by studentId having count(studentId)>1
--找出重复的数据
)
and borrowid not in(
select min(borrowId) from borrowRecord group by studentId having count(studentId)>1
--保留重复数据中的一条数据
)
3、删除所有重复的数据
delete from table_name
where id in(
select id from table_name group by id having count(id)>1
)