‘壹’ sql 查询,100多个字段,查询时怎么去掉某个不需要的字段
这个确实比较麻烦。
如果你已知不要的字段较少,可以通过查询 syscolumns 表,然后拼动态SQL语句。
‘贰’ sql中 如何删除重复的 多字段 数据
你照我这个例子写
D_DATE V_NAME V_SCORES
2008-8-8 拜仁 胜
2008-8-9 奇才 胜
2008-8-9 湖人 胜
2008-8-10 拜仁 负
2008-8-8 拜仁 负
2008-8-12 奇才 胜
DELETE FROM T_SCORES T1
WHERE T1.ROWID IN (SELECT ROWID
FROM (SELECT ROWID,
T.*,
ROW_NUMBER() OVER(PARTITION BY T.V_NAME ORDER BY 1) DATA_ORDER
FROM T_SCORES T)
WHERE DATA_ORDER <> 1)
‘叁’ sql语句如何删除数据库字段。
delete
(字段)
from
(表名)
where
(字段=要删除字段的条件)
这样应该就可以了
建议你看看SQL必知必会,里面对于SQL语句有相当详细的介绍
而且很容易看懂
‘肆’ 如何在Sql中将重复的所有字段删除
用SQL语句,删除掉重复项只保留一条
在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢
1、查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断
select * from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录
delete from people
where peopleName in (select peopleName from people group by peopleName having count(peopleName) > 1)
and peopleId not in (select min(peopleId) from people group by peopleName having count(peopleName)>1)
3、查找表中多余的重复记录(多个字段)
select * from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
4、删除表中多余的重复记录(多个字段),只留有rowid最小的记录
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、查找表中多余的重复记录(多个字段),不包含rowid最小的记录
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)
6.消除一个字段的左边的第一位:
update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%'
7.消除一个字段的右边的第一位:
update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%村'
8.假删除表中多余的重复记录(多个字段),不包含rowid最小的记录
update vitae set ispass=-1
where peopleId in (select peopleId from vitae group by peopleId
‘伍’ SQL重复记录查询 查询多个字段、多表查询、删除重复记录的方法
SQL重复记录查询
1、查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断
select
*
from
people
where
peopleId
in
(select
peopleId
from
people
group
by
peopleId
having
count(peopleId)
>
1)
例二:
select
*
from
testtable
where
numeber
in
(select
number
from
people
group
by
number
having
count(number)
>
1
)
可以查出testtable表中number相同的记录
2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录
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、查找表中多余的重复记录(多个字段)
select
*
from
vitae
a
where
(a.peopleId,a.seq)
in
(select
peopleId,seq
from
vitae
group
by
peopleId,seq
having
count(*)
>
1)
4、删除表中多余的重复记录(多个字段),只留有rowid最小的记录
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、查找表中多余的重复记录(多个字段),不包含rowid最小的记录
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)
(二)
比方说
在A表中存在一个字段“name”,
而且不同记录之间的“name”值有可能会相同,
现在就是需要查询出在该表中的各记录之间,“name”值存在重复的项;
Select
Name,Count(*)
From
A
Group
By
Name
Having
Count(*)
>
1
如果还查性别也相同大则如下:
Select
Name,sex,Count(*)
From
A
Group
By
Name,sex
Having
Count(*)
>
1
(三)
方法一
declare
@max
integer,@id
integer
declare
cur_rows
cursor
local
for
select
主字段,count(*)
from
表名
group
by
主字段
having
count(*)
>;
1
open
cur_rows
fetch
cur_rows
into
@id,@max
while
@@fetch_status=0
begin
select
@max
=
@max
-1
set
rowcount
@max
delete
from
表名
where
主字段
=
@id
fetch
cur_rows
into
@id,@max
end
close
cur_rows
set
rowcount
0
方法二
有两个意义上的重复记录,一是完全重复的记录,也即所有字段均重复的记录,二是部分关键字段重复的记录,比如Name字段重复,而其他字段不一定重复或都重复可以忽略。
1、对于第一种重复,比较容易解决,使用
select
distinct
*
from
tableName
就可以得到无重复记录的结果集。
如果该表需要删除重复的记录(重复记录保留1条),可以按以下方法删除
select
distinct
*
into
#Tmp
from
tableName
drop
table
tableName
select
*
into
tableName
from
#Tmp
drop
table
#Tmp
发生这种重复的原因是表设计不周产生的,增加唯一索引列即可解决。
2、这类重复问题通常要求保留重复记录中的第一条记录,操作方法如下
假设有重复的字段为Name,Address,要求得到这两个字段唯一的结果集
select
identity(int,1,1)
as
autoID,
*
into
#Tmp
from
tableName
select
min(autoID)
as
autoID
into
#Tmp2
from
#Tmp
group
by
Name,autoID
select
*
from
#Tmp
where
autoID
in(select
autoID
from
#tmp2)
最后一个select即得到了Name,Address不重复的结果集(但多了一个autoID字段,实际写时可以写在select子句中省去此列)
(四)
查询重复
select
*
from
tablename
where
id
in
(
select
id
from
tablename
group
by
id
having
count(id)
>
1
)
以上就是小编为大家带来的SQL重复记录查询
查询多个字段、多表查询、删除重复记录的方法的全部内容了,希望对大家有所帮助,多多支持脚本之家~
‘陆’ SQL语句(mysql)怎么去掉字段内一部分内容
摘要 穷。可以使用字符串处理函数来去掉字段的不分内容,例如insert(),replace()等等函数也可以组合使用它们。
‘柒’ 怎么使用SQL语句批量删除多个表的相同字段
在phpmyadmin中先运行(假设前缀是\"cdb_\"):
select
concat(\'drop
table
\',
table_name,
\';\')
from
information_schema.tables;
where
table_name
like
\'cdb_%\'
然后把执行的结果从网页中复制出来,粘贴到记事本中,把记事本中的文件另存为:droptable.sql
。(文件类型中选“所有文件”)
在phpmyadmin中,顶部的菜单中,有“import”,点击后,你把新建的文件上传上去,然后点击右下方的“执行”
‘捌’ mysql 怎么通过sql语句批量去掉某一个表中某一个字段的多余字符
采用替换,把”<img
src="“替换为空格,"
width="300"
height="300"
/>也替换为空格,曾经在网上看到过这样的SQL,替换字段中字符串中的某些字符
update
表名
set
要修改的字段名=
replace(要修改的字段名,‘<img
src="’,'')
update
表名
set
要修改的字段名=
replace(要修改的字段名,‘width="300"
height="300"
/>’,'')
update
表名
set
要修改的字段名=
replace(要修改的字段名,"替换前的字符","替换后的字符")
这样试试看
‘玖’ sql如何进行多个字段去重
select
distinct
列名1,列名2,列名3....
from
表名1
使用关键字:distinct即可去除结果集中的重复结果
‘拾’ 运行sql时出现多个空值,如何去除
1、创建测试表,
create table test_null(work_no VARCHAR(20), chinese_name varchar2(20), department_name varchar2(20), department_id varchar2(20), fee varchar2(20));