Mysql 计算次数，出现一个数字并将其更新到其他列

我不知道如何在mysql中做到这一点，我已经搜索过了，但似乎找不到解决方案。 , 我有一张这样的桌子

id pid occurrence  
1  23  blank
2  23  blank
3  44  blank

基本上，对于id 1,2，事件的值应为2，对于id 3，事件的值应为1。

---

任何帮助都将不胜感激。我可以很容易地调用count和GROUP BY，并获得每次出现的次数，但我想为每个pid在正确的位置更新列出现次数。

要获得正确的

出现次数

值，您可以执行以下操作

select pid, count(*) as occurrence
from your_table
group by pid

要更新表，请执行以下操作：

update your_table t1
join 
(
    select pid, count(*) as occurrence
    from your_table
    group by pid
) t2 on t1.pid = t2.pid
set t1.occurrence = t2.occurrence

---

要获得正确的

出现次数

值，可以执行以下操作

select pid, count(*) as occurrence
from your_table
group by pid

要更新表，请执行以下操作：

update your_table t1
join 
(
    select pid, count(*) as occurrence
    from your_table
    group by pid
) t2 on t1.pid = t2.pid
set t1.occurrence = t2.occurrence

---

要获得正确的

出现次数

值，可以执行以下操作

select pid, count(*) as occurrence
from your_table
group by pid

要更新表，请执行以下操作：

update your_table t1
join 
(
    select pid, count(*) as occurrence
    from your_table
    group by pid
) t2 on t1.pid = t2.pid
set t1.occurrence = t2.occurrence

---

要获得正确的

出现次数

值，可以执行以下操作

select pid, count(*) as occurrence
from your_table
group by pid

要更新表，请执行以下操作：

update your_table t1
join 
(
    select pid, count(*) as occurrence
    from your_table
    group by pid
) t2 on t1.pid = t2.pid
set t1.occurrence = t2.occurrence

---

如果要在表中设置值，请将

update

与

join

一起使用：

update table t join
       (select pid, count(*) as cnt
        from table 
        group by pid
       ) tt
       on tt.pid = t.pid
    set t.occurrence = tt.cnt;

---

如果要在表中设置值，请将

update

与

join

一起使用：

update table t join
       (select pid, count(*) as cnt
        from table 
        group by pid
       ) tt
       on tt.pid = t.pid
    set t.occurrence = tt.cnt;

---

如果要在表中设置值，请将

update

与

join

一起使用：

update table t join
       (select pid, count(*) as cnt
        from table 
        group by pid
       ) tt
       on tt.pid = t.pid
    set t.occurrence = tt.cnt;

---

如果要在表中设置值，请将

update

与

join

一起使用：

update table t join
       (select pid, count(*) as cnt
        from table 
        group by pid
       ) tt
       on tt.pid = t.pid
    set t.occurrence = tt.cnt;