sql重复数据查询,
sql分组数据查询,
sql分组数据的总条数,
sql分组后数据的条数（条数大于1的显示）,
删除多余重复数据 ,保留最小ID
sql语句代码
USE[quanxi_apps]
--1 获取原始数据和原始数据的总条数
select ID,title
from [dbo].[T_BL_symptom_new]
order by title
select count(title) as '原始数据：总条数'
from [dbo].[T_BL_symptom_new]
--2 获取分组数据和分组数据的总条数
select title
from [dbo].[T_BL_symptom_new]
group by title
order by title
select count(*) as '分组数据：总条数'
from
(
select title
from [dbo].[T_BL_symptom_new]
group by title
) as T_BL_symptom_new2020
--3 获取分组数据和分组后数据的条数（条数大于1的显示）
select title ,count(title)as '分组数据：条数'
from [dbo].[T_BL_symptom_new]
group by title
having count(title)>1
--4 删除多余重复数据,保留最小ID
delete
from T_BL_symptom_new
where title in
(
select title
from [dbo].[T_BL_symptom_new]
group by title
having count(title)>1
)
and
minID not in
(
select min(minID)
from [dbo].[T_BL_symptom_new]
group by title
having count(title)>1
)删除重复数据保留最小ID--步骤
1.设计表
右键表[表名]>>设计，在表中增加列【minID 】设置成主键、自增、增量1
（其中：主键可忽略）
2.执行sql删除语句
delete
from [表名]
where (重复字段名) in
(
select (重复字段名)
from [表名]
group by (重复字段名)
having count((重复字段名))>1
)
and
(最小ID字段名) not in
(
select min((最小ID字段名))
from [表名]
group by (重复字段名)
having count((重复字段名))>1
)实例sql代码
delete
from T_BL_symptom_new
where title in
(
select title
from [dbo].[T_BL_symptom_new]
group by title
having count(title)>1
)
and
minID not in
(
select min(minID)
from [dbo].[T_BL_symptom_new]
group by title
having count(title)>1
)
扩展阅读：
SQL 删除重复记录，并保留其中一条
