Mysql 如果计数（id）在表中有多个，则更新列

我有一张像这样的桌子

ID  CustId  CustName Status
1     a1       A     NULL
2     a1       A     NULL
3     a2       B     NULL
4     a3       B     NULL
5     a4       C     NULL
6     a4       C     NULL
7     a5       D     NULL
8     a6       E     NULL

我想在

count（custid）>1时更新
status=2
，在
count（custid）=1时更新
status=1
我希望输出如下

ID  CustId  CustName Status
1     a1       A     1
2     a1       A     2
3     a2       B     1
4     a3       B     1
5     a4       C     1
6     a4       C     2
7     a4       D     2
8     a6       E     1

使用联接更新：

它将在sql server中工作：

update tablename set status=cstatus
from tablename inner join
(
select custid, count(custid) as cstatus
from tablename)b on tablename.custid=b.custid

在Mysql中，以下内容将起作用

UPDATE tablename
    JOIN (
    select custid, count(custid) as cstatus
    from tablename)b on tablename.custid=b.custid
SET set status=cstatus

使用联接更新：

它将在sql server中工作：

update tablename set status=cstatus
from tablename inner join
(
select custid, count(custid) as cstatus
from tablename)b on tablename.custid=b.custid

在Mysql中，以下内容将起作用

UPDATE tablename
    JOIN (
    select custid, count(custid) as cstatus
    from tablename)b on tablename.custid=b.custid
SET set status=cstatus

试试这个：

declare @tbl table (ID int,  CustId char(2), CustName char(1), Status int);
insert into @tbl values
(1,'a1','A',NULL),
(2,'a1','A',NULL),
(3,'a2','B',NULL),
(4,'a3','B',NULL),
(5,'a4','C',NULL),
(6,'a4','C',NULL),
(7,'a5','D',NULL),
(8,'a6','E',NULL);

update t1 set t1.Status = case when t2.st > 1 then 2 else 1 end
from @tbl t1
join (select ID, COUNT(*) over (partition by custname) st from @tbl) t2
on t1.ID = t2.ID

select * from @tbl

试试这个：

declare @tbl table (ID int,  CustId char(2), CustName char(1), Status int);
insert into @tbl values
(1,'a1','A',NULL),
(2,'a1','A',NULL),
(3,'a2','B',NULL),
(4,'a3','B',NULL),
(5,'a4','C',NULL),
(6,'a4','C',NULL),
(7,'a5','D',NULL),
(8,'a6','E',NULL);

update t1 set t1.Status = case when t2.st > 1 then 2 else 1 end
from @tbl t1
join (select ID, COUNT(*) over (partition by custname) st from @tbl) t2
on t1.ID = t2.ID

select * from @tbl

用这个

SELECT tbl.id
      ,tbl.cust_id
      ,tbl.cust_name
      ,(SELECT COUNT(cust_id)
        FROM Mytable
        WHERE cust_id = tbl.cust_id) AS status
FROM MyTable tbl;
-- to update table
-- first create a dummy table
create table tbl as select tbl.id, tbl.cust_id, tbl.cust_name, (select count(cust_id) from Mytable where cust_id = tbl.cust_id) as status from MyTable tbl;
-- drop original
drop table mytable;
-- rename dummy
alter table tbl rename to mytable;

用这个

SELECT tbl.id
      ,tbl.cust_id
      ,tbl.cust_name
      ,(SELECT COUNT(cust_id)
        FROM Mytable
        WHERE cust_id = tbl.cust_id) AS status
FROM MyTable tbl;
-- to update table
-- first create a dummy table
create table tbl as select tbl.id, tbl.cust_id, tbl.cust_name, (select count(cust_id) from Mytable where cust_id = tbl.cust_id) as status from MyTable tbl;
-- drop original
drop table mytable;
-- rename dummy
alter table tbl rename to mytable;

您使用的是mysql还是sql server？请不要标记未涉及的产品。发布您的查询如何正确显示您尝试的查询和标记问题。您使用的是mysql还是sql server？请不要标记未涉及的产品。发布您的查询如何正确显示您尝试的查询和标记问题。