技術標籤：mysql

最近比較忙，今天繼續有空
題目來源https://blog.csdn.net/mrbcy/article/details/68965271
今天的題目：查詢“張旭“教師任課的學生成績
我的做法：

SELECT
	students.sno as sno,
	sname,
	cname,
	degree 
FROM
	students,
	scores,
	courses,
	teachers 
WHERE
	students.sno = scores.sno 
	AND scores.cno = courses.cno 
	AND courses.tno = teachers.
 
tno 
	AND teachers.tname = '張旭';

形成結果;

students.sno as sno
為什麼這裡會這麼寫
因為如果單獨寫sno，會報錯：
1052 - Column ‘sno’ in field list is ambiguous
造成sno取值指向不明，所以要特指哪個表裡的sno