README.md

SQL Tutorial

之前用了用 MySQL ，没有用 GUI 软件（因为 navicat 要钱）。命令行觉得有趣，因为其中有很多操作并不直观，比如为啥 source 这么慢？为啥设置 innodb_flush_log_at_trx_commit = 0 啥的就行了？

必须理解才行。于是咱系统学一学数据库，先从基础操作和基础原理说起。

https://sqlzoo.net/wiki/SQL_Tutorial

• SELECT basics
• FUNCTIONS
• JOIN
• INSERT, UPDATE, DELETE, CREATE, DROP
• ALTER, UNION, Full Text Search, Equi Join, Column Name with Spaces

答案与代码参考了：

• Find the routes involving two buses that can go from A to B
• github.com/jisaw/sqlzoo-solutions

SELECT basics

./drafts/sql.001.md

• 基础的查询与运算
• Umlaut 非ASC码字符 Non-ASCII characters
• Apostrophe 撇号
• 排序 ORDER BY 与逆序 DESC
• 取前 K 个数用 LIMIT
• CASE 与 ORDER BY 混用
• 嵌套查询、去重 DISTINCT、聚合 GROUP BY
• 混合练习：CONCAT与处理NULL值
• correlated sub-query or synchronized sub-query（子查询同步？）

FUNCTIONS

./drafts/sql.002.md

• Using SUM, Count, MAX, DISTINCT and ORDER BY
• Using GROUP BY and HAVING
• CONCAT, SUBSTRING, LOWER, POSITION
• ROUND, COALESCE, CASE
• CURRENT_TIMESTAMP, CURRENT_DATE, DATE_FORMAT, EXTRACT
• REPLACE, INSTR, IFNULL, NVL, NULLIF

JOIN

./drafts/sql.003.md

• JOIN basics
• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• JOIN 与 COALCASE、CASE
• SELF JOIN

INSERT, UPDATE, DELETE, CREATE, DROP

./drafts/sql.004.md

• INSERT
• UPDATE
• DELETE
• CREATE
• DROP

ALTER, UNION, Full Text Search, Equi Join, Column Name with Spaces

./drafts/sql.005.md

• ALTER
• UNION
• Full Text Search
• Equi Join
• Column Name with Spaces