作者evilove (愿意感动就是一种享受)
看板Database
标题[SQL ] 请问这两个语法结果一样吗？
时间Fri Jun 17 11:12:59 2016
资料库名称：MySQL
内容/问题描述：您好我是初学者，想知道下面两个语法的结果是一样的吗？
谢谢！
SELECT COUNT(DISTINCT pid) AS Hispanic
FROM (SELECT patients.pid, patients.ethnicity, ethnicity.Name, ethnicity.Code
FROM ethnicity
INNER JOIN patients
ON patients.ethnicity=ethnicity.Code)
WHERE Name='Hispanic or Latino';
SELECT COUNT(DISTINCT patients.pid) AS Hispanic
FROM ethnicity, patients
WHERE patients.ethnicity=ethnicity.Code
AND ethnicity.Name='Hispanic or Latino';
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1F：→ Ammenze: 应该是一样的 06/17 12:19
2F：→ evilove: 谢谢您～ 06/17 23:16