MySQL 根据多字段查询重复数据的示例代码

SELECT name, COUNT(*) as count
FROM users
GROUP BY name
HAVING count > 1;

SELECT name, email, COUNT(*) as count
FROM users
GROUP BY name, email
HAVING count > 1;

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50),
    email VARCHAR(50)
);
INSERT INTO users (name, email) VALUES
    ('Alice', 'alice@example.com'),
    ('Bob', 'bob@example.com'),
    ('Alice', 'alice@example.com'),
    ('Charlie', 'charlie@example.com'),
    ('David', 'david@example.com'),
    ('Alice', 'alice@example.com');

SELECT name, email, COUNT(*) as count
FROM users
GROUP BY name, email
HAVING count > 1;

SELECT * FROM tb_table WHERE sample_code IN(
SELECT sample_code FROM tb_table GROUP BY sample_code HAVING COUNT(sample_code) > 1
);

delete from tb_table where id not in (select maxid from (select max(id) as maxid from tb_table group by sample_code) b);

SELECT * from (SELECT *, CONCAT(name,code) as nameAndCode from tb_table) t WHERE t.nameAndCode in 
(
    SELECT nameAndCode from (SELECT CONCAT(name,code) as nameAndCode from tb_table) tt GROUP BY nameAndCode HAVING count(nameAndCode) > 1
)

DELETE from tb_table WHERE id not in 
(
    SELECT maxid from (SELECT MAX(id) as maxid, CONCAT(name,code) as nameAndCode from tb_table GROUP BY nameAndCode) t
)

select * from xi a where (a.username) in  (select username from xi group by username  having count(*) > 1)

select  count(username) as '重复次数',username from xi group by username  having count(*)>1 order by username desc

select * from people
where peopleId in (select  peopleId  from  people  group  by  peopleId  having  count(peopleId) > 1)

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)

select * from vitae a
where (a.peopleId,a.seq) in  (select peopleId,seq from vitae group by peopleId,seq  having count(*) > 1)

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)

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)

Select Name,Count(*) From A Group By Name Having Count(*) > 1

Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1

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(*) >;
open cur_rows fetch cur_rows into @id,@maxwhile @@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,@maxend
close cur_rows
set rowcount 0

select distinct * from tableName

select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp

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)　

select * from tablename where id in (select id from tablenamegroup by idhaving count(id) > 1)

SELECT * FROM tb_table WHERE sample_code IN( SELECT sample_code FROM tb_table GROUP BY sample_code HAVING COUNT(sample_code) > 1 );

SELECT * from (SELECT *, CONCAT(name,code) as nameAndCode from tb_table) t WHERE t.nameAndCode in 
(
    SELECT nameAndCode from (SELECT CONCAT(name,code) as nameAndCode from tb_table) tt GROUP BY nameAndCode HAVING count(nameAndCode) > 1
)