顯示了鍵的行與多個行

Question

Table kal 
id integer primary key 
init char 4 indexed 
job char4 

id init job 
--+----+------ 
1 | aa | job1 
2 | aa | job2 
3 | bb | job1 
4 | cc | job3 
5 | cc | job5 

我想告訴這裏的init有超過一排的所有行：

id init job 
--+----+------ 
1 | aa | job1 
2 | aa | job2 
4 | cc | job3 
5 | cc | job5 

我想：

select * from kal where init in (select init from kal group by init having 
count(init)>2); 

實際上，表有60000行，查詢是

count(init)<40, 

但它需要大量的時間，phpmyadmin和我的耐心耗盡。

兩個

select init from kal group by init having count(init)>2) 

和

select * from kal where init in ('aa','bb','cc') 

運行在 「沒有時間」，小於0.02秒。

我已經嘗試了不同的子查詢，但都需要「無限」的時間，超過幾分鐘;我其實從來沒有讓他們完成。

Answer 1

下面是一個例子，你可以在see it行動：

查詢

SELECT a.id, a.init, a.job 
FROM kal a 
INNER JOIN 
    (SELECT init, COUNT(init) 
    FROM kal 
    GROUP BY init 
    HAVING COUNT(init) > 1) b ON b.init = a.init 

結果

| ID | INIT | JOB | 
-------------------- 
| 1 | aa | job1 | 
| 2 | aa | job2 | 
| 4 | cc | job3 | 
| 5 | cc | job5 |

Answer 2

你嘗試EXISTS？

select * 
from yourtable t1 
where exists (select count(*) 
       from yourtable t2 
       where t1.init = t2.init 
       group by t2.init 
       having count(*) >= 2); 

看到SQL Fiddle with Demo

甚至這樣的：

select * 
from yourtable t1 
left join 
(
    select count(*) cnt, init 
    from yourtable 
    group by init 
) t2 
    on t1.init = t2.init 
where t2.cnt > 1 

看SQL Fiddle with Demo