Mysql-计数NULL总是返回0?
我试图得到这个结果:Mysql-计数NULL总是返回0?,mysql,Mysql,我试图得到这个结果: NULL 350 google 98 yahoo 5 bing 4 使用此查询: SELECT engine, COUNT(engine) AS count FROM visits GROUP BY engine ORDER BY count DESC 但它的回报是: google 98 yahoo 5 bing 4 NULL 0 如何解决此问题?使用计数(1)代替: SELECT engine, COUNT(1) AS count
NULL 350
google 98
yahoo 5
bing 4
使用此查询:
SELECT engine, COUNT(engine) AS count
FROM visits
GROUP BY engine
ORDER BY count DESC
但它的回报是:
google 98
yahoo 5
bing 4
NULL 0
如何解决此问题?使用计数(1)
代替:
SELECT engine, COUNT(1) AS count
FROM visits
GROUP BY engine
ORDER BY count DESC;
count(*)
或count(1)
或count(aNotNullableColumn)
将起作用。