楼主:
evilove (愿意感动就是一种享受)
2016-06-17 11:12:59数据库名称：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';