SQL去除重复记录
if
not
object_id(
'Tempdb..#T'
)
is
null
drop
table
#T
Go
Create
table
#T([ID]
int
,[
Name
] nvarchar(1),[Memo] nvarchar(2))
Insert
#T
select
1,N
'A'
,N
'A1'
union
all
select
2,N
'A'
,N
'A2'
union
all
select
3,N
'A'
,N
'A3'
union
all
select
4,N
'B'
,N
'B1'
union
all
select
5,N
'B'
,N
'B2'
Go
--I、Name相同ID最小的记录(推荐用1,2,3),保留最小一条
方法1:
delete
a
from
#T a
where
exists(
select
1
from
#T
where
Name
=a.
Name
and
ID
方法2:
delete
a
from
#T a
left
join
(
select
min
(ID)ID,
Name
from
#T
group
by
Name
) b
on
a.
Name
=b.
Name
and
a.ID=b.ID
where
b.Id
is
null
方法3:
delete
a
from
#T a
where
ID
not
in
(
select
min
(ID)
from
#T
where
Name
=a.
Name
)
方法4(注:ID为唯一时可用):
delete
a
from
#T a
where
ID
not
in
(
select
min
(ID)
from
#T
group
by
Name
)
方法5:
delete
a
from
#T a
where
(
select
count
(1)
from
#T
where
Name
=a.
Name
and
ID0
方法6:
delete
a
from
#T a
where
ID<>(
select
top
1 ID
from
#T
where
Name
=a.
name
order
by
ID)
方法7:
delete
a
from
#T a
where
ID>
any
(
select
ID
from
#T
where
Name
=a.
Name
)
select
*
from
#T