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[英]Get data between each 5 year in SQL Server (like 1990-1995, 1995-2000, 2000-2005)
[英]Remove duplicates - SQL server 2000-2005
仅适用于通过SQL查询的MSSQL 2000-2005,无存储过程
没有游标和临时表
桌子
create table my_table
(
row_id int identity(1,1),
_key varchar(20),
_total decimal(18,2)
)
插入数据
insert into my_table (_key,_total) Values('qwe',10)
insert into my_table(_key,_total) Values ('qwe',10)
insert into my_table(_key,_total) Values ('asd',10)
insert into my_table(_key,_total) Values('asd',10)
insert into my_table(_key,_total) Values('zxc',10)
insert into my_table(_key,_total) Values('zxc',10)
insert into my_table(_key,_total) Values('qwe',100)
insert into my_table(_key,_total) Values('qwe',100)
insert into my_table(_key,_total) Values('asd',100)
insert into my_table(_key,_total) Values('asd',100)
insert into my_table(_key,_total) Values('zxc',100)
insert into my_table(_key,_total) Values('zxc',100)
insert into my_table(_key,_total) Values('qwe',50)
insert into my_table(_key,_total) Values('qwe',50)
insert into my_table(_key,_total) Values('asd',50)
insert into my_table(_key,_total) Values('asd',50)
insert into my_table(_key,_total) Values('zxc',50)
insert into my_table(_key,_total) Values('zxc',50)
我需要通过_key字段删除重复项,并保留最大_total的行,其中最大的row_id。
我需要得到这个结果集
8 qwe 100.00
10 asd 100.00
12 zxc 100.00
要删除它们,这就是我认为“删除重复项”的意思:
DELETE FROM dbo.my_table
WHERE NOT EXISTS(SELECT NULL
FROM dbo.my_table x
JOIN (SELECT _key,
MAX(_total) AS max_total
FROM dbo.my_table
GROUP BY _key) y ON y._key = x._key
AND y.max_total = x._total
WHERE x._key = my_table._key
AND x._total = my_table._total
GROUP BY x._key, x._total
HAVING MAX(x.row_id) = my_table.row_id)
选择您要列出的行的查询是:
SELECT MAX(x.row_id),
x._key,
x._total
FROM dbo.my_table x
JOIN (SELECT _key,
MAX(_total) AS max_total
FROM dbo.my_table
GROUP BY _key) y ON y._key = x._key
AND y.max_total = x._total
GROUP BY x._key, x._total
如果您首先用通俗易懂的语言表达您想要的内容,那将变得更加容易
...变成...
我还没有运行...我将其留给您查找任何缺少的逗号等
SELECT
MAX(row_id) AS MaxRowid, M._key, M._total
FROM
(
SELECT
_key, max(_total) AS TTotal
FROM
my_table
GROUP BY
_key
) foo
JOIN
my_table M ON foo._key = M._key AND foo.TTotal = M._total
GROUP BY
M._key, M._total
对于SQL Server 2005+,我可以使用CTE进行更改
;WITH cFoo AS
(
SELECT
row_id, _key, _total,
ROW_NUMBER() OVER (PARTITION BY _key ORDER BY _total DESC, row_id DESC) AS bar
)
SELECT
row_id, _key, _total
FROM
cFoo
WHERE
bar = 1
您可以通过使用两个查询来实现:
--Delete all lesser total duplicates
delete T1
from My_Table T1, My_Table T2
where T1._key = T2._key
and T1._total < T2._total
--Delete all equal total with lesser row_id duplicates
delete T1
from My_Table T1, My_Table T2
where T1._key = T2._key
and T1.row_id < T2.row_id
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