求一sql指令：统计主贴的回帖数量
有数据库表t，字段如下，想更新replies字段的值，如何写sql指令？

C# code

这是原来表的数据：id    replies    zid1    0    02    0    03    0    14    0    15    0    26    0    1这是更新后应该有的结果：id    replies    zid1    3    02    1    03    0    14    0    15    0    26    0    1

若zid=0，说明是主贴
若zid=1，表示该贴是id=1的主贴的回帖

[解决办法]
你定义一个游标也可以实现：

declare @id int
declare cur cursor
for
select id from t where zid=0
open cur
fetch next from cur into @id
while @@Fetch_status = 0
begin
update t set replies=(select count(*) from t where zid =@id) where zid=0 and id=@id
fetch next from cur into @id
end
select * from t
close cur
deallocate cur
[解决办法]
update tb set replies=(select isnull(count(*),0) from Tb a where a.id=id) where zid=0

[解决办法]

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引用:
update tb set replies=(select isnull(count(*),0) from Tb a where a.id=id) where zid=0


经多次变样测试，下面的指令不能得到正确的结果：
update t set replies=(select count(*) from t a where a.zid=id) w……