Mysql 我想为同一列获取多个值的记录

我试图根据自己的两个值从数据库中获取值，这些值必须与数据库的id匹配

id   contactid  flag        flag_type 
-----------------------------------
1    99         Volunteer   1 
2    99         Uploaded    2 
3    100        Via Import  3 
4    100        Volunteer   1  
5    100        Uploaded    2

因此，我希望从这里获得id为1和2的行，并忽略其余的值。但假设id为2的行不存在，则该语句不会返回任何行

我尝试过以下说法，但似乎不起作用：

SELECT * FROM docs WHERE id IN (1) AND id IN (2);

你应该使用或

    SELECT * FROM docs 
    WHERE id IN (1) OR  id IN (2);

或

或者如果您需要id为1,2的contactid记录，则

    select * from docs 
    inner join (
        select  contactid 
        from docs 
        where id IN (1, 2) 
        having count(distinct id ) = 2
    ) t on t.contactid = docs.contactid

您需要子查询

select id from table_name where contactid in (
select contactid
from table_nae
group by contactid
having count(*)=2
)

---

子查询将仅选择计数为2的联系人id，在主查询的情况下，将帮助选择所需的id

如果您希望联系人正好具有这些标志，您可以执行以下操作：

select contactid
from t
group by contactid
having sum(flag = 1) > 0 and         -- has 1
       sum(flag = 2) > 0 and         -- has 2
       sum(flag not in (1, 2)) = 0;  -- has nothing else

有多种方法可以获取原始行-使用in、exists或join：

---

使用逗号分隔的ID值作为SELECT*从ID位于1,2的文档尝试输入运算符@BarbarosÖzhan我需要两个值都存在，而不仅仅是一个值，因此如果一个值不存在，则语句返回Nothing我需要两个值都存在而不仅仅是一个值，因此如果一个值不存在，则语句返回Nothingnothing@JordanPattinson如果id=2的contactid等于98..怎么办。。？

select contactid
from t
group by contactid
having sum(flag = 1) > 0 and         -- has 1
       sum(flag = 2) > 0 and         -- has 2
       sum(flag not in (1, 2)) = 0;  -- has nothing else

select t.*
from t join
     (select contactid
      from t
      group by contactid
      having sum(flag = 1) > 0 and         -- has 1
             sum(flag = 2) > 0 and         -- has 2
             sum(flag not in (1, 2)) = 0   -- has nothing else
     ) tt
     on t.contactid = tt.contactid;