new_org/wonderful-sql
2
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Delete ch07: 秋招秘籍 B.md

Browse Source
This commit is contained in:
mba1398
2022-02-04 13:52:53 +08:00
committed by GitHub
parent 6a84d83c16
commit 28eb8709e3
1 changed files with 0 additions and 83 deletions
Download Patch File Download Diff File Expand all files Collapse all files

83
ch07: 秋招秘籍 B.md
View File

@@ -1,83 +0,0 @@
# 练习一：行转列
假设 A B C 三位小朋友期末考试成绩如下所示：
```plain
+-----+-----------+------|
| name| subject |score |
+-----+-----------+------|
| A | chinese | 99 |
| A | math | 98 |
| A | english | 97 |
| B | chinese | 92 |
| B | math | 91 |
| B | english | 90 |
| C | chinese | 88 |
| C | math | 87 |
| C | english | 86 |
+-----+-----------+------|
```
请使用 SQL 代码将以上成绩转换为如下格式：
```plain
+-----+-----------+------|---------|
| name| chinese | math | english |
+-----+-----------+------|---------|
| A | 99 | 98 | 97 |
| B | 92 | 91 | 90 |
| C | 88 | 87 | 86 |
+-----+-----------+------|---------|
```
# 练习二：列转行
假设 A B C 三位小朋友期末考试成绩如下所示：
```plain
+-----+-----------+------|---------|
| name| chinese | math | english |
+-----+-----------+------|---------|
| A | 99 | 98 | 97 |
| B | 92 | 91 | 90 |
| C | 88 | 87 | 86 |
+-----+-----------+------|---------|
```
请使用 SQL 代码将以上成绩转换为如下格式：
```plain
+-----+-----------+------|
| name| subject |score |
+-----+-----------+------|
| A | chinese | 99 |
| A | math | 98 |
| A | english | 97 |
| B | chinese | 92 |
| B | math | 91 |
| B | english | 90 |
| C | chinese | 88 |
| C | math | 87 |
| C | english | 86 |
+-----+-----------+------|
```
# 练习三：带货主播
假设，某平台2021年主播带货销售额日统计数据如下：
表名 `anchor_sales`
```plain
+-------------+------------+---------|
| anchor_name | date | sales |
+-------------+------------+---------|
| A | 20210101 | 40000 |
| B | 20210101 | 80000 |
| A | 20210102 | 10000 |
| C | 20210102 | 90000 |
| A | 20210103 | 7500 |
| C | 20210103 | 80000 |
+-------------+------------+---------|
```
定义：如果某主播的某日销售额占比达到该平台当日销售总额的 90% 及以上，则称该主播为明星主播，当天也称为明星主播日。
请使用 SQL 完成如下计算：
a. 2021年有多少个明星主播日？
b. 2021年有多少个明星主播？
# 练习四：MySQL 中如何查看sql语句的执行计划？可以看到哪些信息？
# 练习五：解释一下 SQL 数据库中 ACID 是指什么