MySQL - 返回匹配查询数据的行数? [英] MySQL - Return number of rows matching query data?
问题描述
我有一个查询如下:
I have a query as follows:
SELECT 1 FROM shop_inventory a JOIN shop_items b ON b.id=a.iid AND b.szbid=3362169 AND b.cid=a.cid WHERE a.cid=1 GROUP BY a.bought
$ b $我只需要处理这些数据就可以计算出返回的行数(我可以用 mysqli - > num_rows;
我想知道是否有方法返回匹配查询的行数,而不必运行 num_rows
?
The only thing I need to do with this data is work out the number of rows returned (which I could do with mysqli -> num_rows;
. However, I would like to know if there is a method to return the number of rows that match the query, without having to run num_rows
?
例如,查询应返回一行,结果为 number_of_rows
。
For example, the query should return one row, with one result, number_of_rows
.
I希望这是有道理的!
I hope this makes sense!
推荐答案
select count(*) as `number_of_rows`
from (
select 1
from shop_inventory a
join shop_items b on b.id = a.iid
and b.szbid = 3362169
and b.cid = a.cid
where a.cid = 1
group by a.bought
) a
在这种情况下,由于您没有使用任何聚合函数,并且 GROUP BY
仅仅是为了消除重复,你也可以这样做:
In this case, since you are not using any aggregate functions and the GROUP BY
is merely to eliminate duplicates, you could also do:
select count(distinct a.bought) as `number_of_rows`
from shop_inventory a
join shop_items b on b.id = a.iid
and b.szbid = 3362169
and b.cid = a.cid
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