xeus-sqlite

访问 https://jupyter.org/try-jupyter/lab/ ，试用 JupyterLite xeus-sqlite 。

建库并连接。数据读写只存在内存中，不能写入浏览器存储。内核一关闭，只存在空文件。

%CREATE test.db

或者连接现有数据库。

%LOAD test.db

建表。

CREATE TABLE players (Name STRING, Class STRING, Level INTEGER, Hitpoints INTEGER)

新增记录。

INSERT INTO players (Name, Class, Level, Hitpoints) VALUES ("张三", "战士", 2, 30)

统计行数。

SELECT COUNT(*) as rowcount FROM players

rowcount
1

每个单元格只执行第一个命令。

INSERT INTO players (Name, Class, Level, Hitpoints) VALUES ("李四", "法师", 2, 20);

-- The following will not be inserted
INSERT INTO players (Name, Class, Level, Hitpoints) VALUES ("王五", "巫师", 1, 10);

查看记录。

SELECT Name, Level, Hitpoints FROM players;

Name	Level	Hitpoints
张三	2	30
李四	2	20

新增记录。

INSERT INTO players (Name, Class, Level, Hitpoints) VALUES ("王五", "巫师", 1, 10);

查看记录。

SELECT Name, Level, Hitpoints FROM players;

Name	Level	Hitpoints
张三	2	30
李四	2	20
王五	1	10

分组聚合。

SELECT Level, SUM(Hitpoints) AS `Total Hitpoints`
FROM players
GROUP BY Level
ORDER BY `Total Hitpoints` DESC;

Level	Total Highpoints
2	50
1	10

是否存在某表 players 。

%TABLE_EXISTS players

The table players exists.

是否存在某表 npcs 。

%TABLE_EXISTS npcs

The table npcs doesn't exist.