在mysql查询中计算相同的值

Question

所以我有一个像

SELECT * FROM `catalog` WHERE `id` IN ('2','2','3','3','3');

并且这只返回2行，ID为2和3.有可能使它返回5行（2个ID为“2”，3个ID为“3”）或者将计数添加为新列？

Answer 1

不确定为什么你会想要做这样的事情，但不是使用'in'子句，你可以使用内部查询：

select *
from `catalog` c,
(
    select 2 ids
    union all
    select 2
    union all
    select 3
    union all
    select 3
    union all
    select 3
) k
where c.id = k.ids

Answer 2

尝试这样的事情：

SELECT t.p,count(*)  FROM 
    catalog, 
    (SELECT 2 as id
    Union all select 2 as id
    Union all select 3 as id
    Union all select 3 as id
    Union all select 3 as id)as t 
where catalog.id = t.id

Answer 3

可以使用临时表来完成：

create temporary table arrayt (id int);
insert into arrayt values  ('2'),('2'),('3'),('3'),('3');
select catalog.* from arrayt a LEFT JOIN catalog on (a.id=catalog.id);

如果你需要数数

select count(catalog.id) as count,catalog.id as id from arrayt a LEFT JOIN catalog on (a.id=catalog.id) group by catalog.id;