[英]How to Count Rows from two Tables with one Command in MySQL
我想從不同的表中計數2個表,即時通訊選擇date
然后將其分組。
這是我嘗試的
SELECT
(SELECT date(date), COUNT(sh_sh) FROM sh_url GROUP BY date(date)) AS URLs,
(SELECT date(date), COUNT(ip) FROM tracking GROUP BY date(date)) AS IP
FROM dual
但我得到錯誤
1241-操作數應包含1列
用一個命令就能做到嗎?
輸出應該是這樣的
date(url) count(sh_sh) date(ip) count(ip)
--------- ------------ ---------- ----------
2018-04-25 123 2018-04-25 123123
2018-04-26 456 2018-04-26 321
2018-04-27 789 2018-04-27 3125
我用兩個子查詢的連接來表達您的問題:
SELECT
t1.date,
t1.url_cnt,
COALESCE(t2.ip_cnt, 0) AS ip_cnt
FROM
(
SELECT date, COUNT(*) url_cnt
FROM sh_url
GROUP BY date
) t1
LEFT JOIN
(
SELECT date, COUNT(*) ip_cnt
FROM tracking
GROUP BY date
) t2
ON t1.date = t2.date;
當使用子查詢作為值時,它只能返回一行和一列。 您需要使用JOIN
:
SELECT urls.date, urls.count AS sh_count, ip.count AS ip_count
FROM (SELECT date(date) AS date, COUNT(*) AS count FROM sh_url GROUP BY date(date)) AS urls
JOIN (SELECT date(date) AS date, COUNT(*) AS count FROM tracking GROUP BY date(date)) AS ip
ON urls.date = ip.date
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