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ch08: 秋招秘籍 C.md
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@@ -72,16 +72,14 @@ INSERT INTO t_act_records VALUES('u1004', 20210105);
# 练习四：hive 数据倾斜的产生原因及优化策略？
# 练习五：left join 是否会出现多出的行？
假设 A表有5行（关联列 name 有2行为空），B表有6行（关联列 name 有3行为空）那么 A left join B on A.name = B.name 会返回多少行结果？
# 练习五：LEFT JOIN 是否可能会出现多出的行？为什么？
假设 A表有6行（关联列 name 有2行为空），B表有6行（关联列 name 有3行为空）,
那么 `SELECT * FROM A LEFT JOIN B on A.name = B.name` 会返回多少行结果？
可以参考下图
A表
[A表](./img/Question_C/C05A.jpg)
B表
[B表](./img/Question_C/C05B.jpg)
A表：![图片](./img/Question_C/C05A.jpg) B表：![图片](./img/Question_C/C05B.jpg)