2018-10-26数据库备份
2018-10-31 本文已影响0人
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思维导图
day10数据库备份.png
4个连接在一起
SELECT *
FROM
(
(
(
students st
JOIN scores sc
ON st.sno = sc.sno
)
JOIN courses co
ON sc.cno = co.cno
)
JOIN teachers te
ON te.tno = co.tno
);
