[英]COUNT or SUM of fields in MySql
我的數據庫中有一個表,最多可以保存60個字段,是或否。 我想計數或從表中的所有字段中減去總和,其中任何字段等於“ yes”;
我嘗試了以下方法,但是沒有運氣:
SELECT count(*) FROM information_schema.columns WHERE table_name = 'portraits';
這將返回列數,但不允許我對等於“ yes”的字段進行計數。
我想知道這樣做在php中更容易嗎? 我目前正在codeigniter中執行此操作,並且我不知道如何讀取鍵/值,因為它是一個對象。 有任何想法嗎?
SELECT count(*)
FROM information_schema.columns
WHERE table_name = 'portraits'
AND (field1=0 OR field2=0 OR .... OR fieldN=0);
試試這個...。這個簡單的查詢將起作用..... :)
SELECT
SUM(IF( information_schema = "YES", 1, 0) AS Yes,
SUM(IF( information_schema != "YES", 1, 0) AS No,
FROM portraits
嘗試這個 :
SELECT state, count(*) FROM information_schema.columns GROUP BY state;
或者以更復雜的方式:
SELECT y.total, n.total
FROM (SELECT count(*) as total FROM information_schema.columns WHERE table_name = 'portraits' AND state = 'yes') as y,
(SELECT count(*) as total FROM information_schema.columns WHERE table_name = 'portraits' AND state = 'no') as n
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