建表: create table t1(a int not null,b int not null,c int not null) 加: alter table t1 add constraint pk_1 primary key (a,b) 删: alter table t1 drop constraint pk_1 再加: alter table t1 add constraint pk_1 primary key (a,b,c)
删除重复的,只留一条:alter table 表 add newfield int identity(1,1)delete 表 where newfield not in( select min(newfield) from 表 group by 你想当主键的列1,你想当主键的列2 )alter table 表 drop column newfield
一: 先要删除重复值蚂蚁的:去除重复值 如果有ID字段,就是具有唯一性的字段delect table where id not in ( select max(id) from table group by col1,col2,col3... ) group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2,如果是判断所有字段也可以这样 select * into #aa from table group by id1,id2,.... delete table insert into table select * from #aa3,没有ID的情况select identity(int,1,1) as id,* into #temp from tabel delect # where id not in ( select max(id) from # group by col1,col2,col3...) delect table inset into table(...) select ..... from #temp col1+','+col2+','...col5 联合主键 select * from table where col1+','+col2+','...col5 in ( select max(col1+','+col2+','...col5) from table where having count(*)>1 group by col1,col2,col3,col4 ) group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2, select identity(int,1,1) as id,* into #temp from tabel select * from #temp where id in ( select max(id) from #emp where having count(*)>1 group by col1,col2,col3...) 二:alter table t1 add constraint pk_1 primary key (a,b)
主键不可以重复的!你可以用ALTER再加一列来当主键!用法看联机帮助!
一: 需先除去重复值 蚂蚁的:去除重复值 如果有ID字段,就是具有唯一性的字段delect table where id not in ( select max(id) from table group by col1,col2,col3... ) group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2,如果是判断所有字段也可以这样 select * into #aa from table group by id1,id2,.... delete table insert into table select * from #aa3,没有ID的情况select identity(int,1,1) as id,* into #temp from tabel delect # where id not in ( select max(id) from # group by col1,col2,col3...) delect table inset into table(...) select ..... from #temp col1+','+col2+','...col5 联合主键 select * from table where col1+','+col2+','...col5 in ( select max(col1+','+col2+','...col5) from table where having count(*)>1 group by col1,col2,col3,col4 ) group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2, select identity(int,1,1) as id,* into #temp from tabel select * from #temp where id in ( select max(id) from #emp where having count(*)>1 group by col1,col2,col3...)二:alter table t1 add constraint pk_1 primary key (a,b)
既然楼主不知道主健是什么,建议你每个表都加上自增字段(identity(1,1))作为主健
alter table t1 add constraint pk_1 primary key (a,b)
create table t1(a int not null,b int not null,c int not null)
加:
alter table t1 add constraint pk_1 primary key (a,b)
删:
alter table t1 drop constraint pk_1
再加:
alter table t1 add constraint pk_1 primary key (a,b,c)
where newfield not in(
select min(newfield) from 表 group by 你想当主键的列1,你想当主键的列2
)alter table 表 drop column newfield
如果有ID字段,就是具有唯一性的字段delect table where id not in ( select max(id) from table group by col1,col2,col3...
)
group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2,如果是判断所有字段也可以这样
select * into #aa from table group by id1,id2,....
delete table
insert into table
select * from #aa3,没有ID的情况select identity(int,1,1) as id,* into #temp from tabel
delect # where id not in (
select max(id) from # group by col1,col2,col3...)
delect table
inset into table(...)
select ..... from #temp
col1+','+col2+','...col5 联合主键
select * from table where col1+','+col2+','...col5 in ( select max(col1+','+col2+','...col5) from table
where having count(*)>1
group by col1,col2,col3,col4
)
group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2,
select identity(int,1,1) as id,* into #temp from tabel
select * from #temp where id in (
select max(id) from #emp where having count(*)>1 group by col1,col2,col3...)
二:alter table t1 add constraint pk_1 primary key (a,b)
蚂蚁的:去除重复值
如果有ID字段,就是具有唯一性的字段delect table where id not in ( select max(id) from table group by col1,col2,col3...
)
group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2,如果是判断所有字段也可以这样
select * into #aa from table group by id1,id2,....
delete table
insert into table
select * from #aa3,没有ID的情况select identity(int,1,1) as id,* into #temp from tabel
delect # where id not in (
select max(id) from # group by col1,col2,col3...)
delect table
inset into table(...)
select ..... from #temp
col1+','+col2+','...col5 联合主键
select * from table where col1+','+col2+','...col5 in ( select max(col1+','+col2+','...col5) from table
where having count(*)>1
group by col1,col2,col3,col4
)
group by 子句后跟的字段就是你用来判断重复的条件,如只有col1,那么只要col1字段内容相同即表示记录相同。2,
select identity(int,1,1) as id,* into #temp from tabel
select * from #temp where id in (
select max(id) from #emp where having count(*)>1 group by col1,col2,col3...)二:alter table t1 add constraint pk_1 primary key (a,b)