在 SQLite 中仅更新和记录 SQL 更改的行

Question

我正在用 R 编写 application/script 来更新 SQLite 数据库。

抱歉 - 我没有这方面的经验。

我的table包含4个字段Id,Name,LVL,Notes:

CREATE TABLE members (
Id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
Name TEXT NOT NULL,
LVL INTEGER NOT NULL,
Notes TEXT
);

INSERT INTO members (Name,LVL,Notes)
VALUES  ('Jean',12,'First stage'),
        ('Jacques',1,'Second stage'),
        ('Amelie',1,'Second stage'),
        ('Louis',13,'Some other note altogether')
;

我想对照另一个 table tmp

CREATE TABLE tmp (
Name TEXT NOT NULL,
LVL INTEGER NOT NULL,
Notes TEXT
);

INSERT INTO tmp (Name,LVL,Notes)
VALUES  ('Jean',13,'First stage'),
        ('Jacques',1,'Second stage'),
        ('Amelie',1,'Third stage'),
        ('Louis',14,'Fourth stage')
;

如果 LVL and/or 注释字段发生变化（如 Jean 和 Louis 的 LVL 以及 Amelie 和 Louis 的注释）我想用新的 members table 更新在我用 member_changes table.

中的时间戳记录以前的值（作为整行）之后的值

实现此目标的最少查询集是多少？

member_changes table 更好的设计是什么？它是否与 members 相同，但添加了 rowID 作为主键和 timestamp 字段？ memberID 自然会允许重复。

非常感谢，

罗布

扩展答案概要

感谢@forpas 的友好回答，我将这个小系统与 2 个额外的触发器放在一起。新信息来自 tmp table。假定成员名称是唯一的；可能不需要 members.Id 上的主键。尽管如此：

-- CREATE members table for current guild members
-- Id is prim key and Name has unique index
CREATE TABLE members (
  Id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
  Name TEXT NOT NULL UNIQUE,
  LVL INTEGER NOT NULL,
  Notes TEXT
);
-- SAMPLE DATA
INSERT INTO members (Name,LVL,Notes) VALUES  
        ('Jean',12,'First stage'),
        ('Jacques',1,'Second stage'),
        ('Amelie',1,'Second stage'),
        ('Louis',13,'Some other note altogether');
-- LOG table to see membership changes over time
CREATE TABLE members_changes (
  timestamp TEXT DEFAULT CURRENT_TIMESTAMP,
  Id INTEGER REFERENCES members(Id),
  Name TEXT NOT NULL,
  LVL INTEGER NOT NULL,
  Notes TEXT
);
-- TABLE through which the updates will come in via rvest
-- presumed cannot contain duplicate names
CREATE TABLE tmp (
  Name TEXT NOT NULL UNIQUE,
  LVL INTEGER NOT NULL,
  Notes TEXT
);
-- TRIGGERS (3)
-- (1) UPDATES MEMBERS if insertion in tmp shows changes
-- also LOGS this change in members_changes
CREATE TRIGGER IF NOT EXISTS tr_insert_tmp AFTER INSERT ON tmp
BEGIN
  INSERT INTO members_changes(Id,Name,LVL,Notes)
  SELECT Id,Name,LVL,Notes
  FROM members
  WHERE Name = NEW.NAME AND (LVL IS NOT NEW.LVL OR Notes IS NOT NEW.Notes);
  
  UPDATE members 
  SET LVL = NEW.LVL, Notes = NEW.Notes
  WHERE Name = NEW.Name AND (LVL IS NOT NEW.LVL OR Notes IS NOT NEW.Notes);
END;
-- (2) LOGS DELETIONS from members
CREATE TRIGGER IF NOT EXISTS tr_delete_members BEFORE DELETE ON members
BEGIN
    INSERT INTO members_changes(Id,Name,LVL,Notes)
    SELECT Id,Name,LVL,Notes || " :Deleted"
    FROM members
    WHERE Name = OLD.Name;
END;
-- (3) LOGS INSERTS into members (new members)
CREATE TRIGGER IF NOT EXISTS tr_insert_members AFTER INSERT ON members
BEGIN
    INSERT INTO members_changes(Id,Name,LVL,Notes)
    SELECT Id,Name,LVL,Notes || " :Inserted"
    FROM members
    WHERE Name = NEW.Name;
END;
-- this shows all defined triggers
select * from sqlite_master where type = 'trigger';

-- QUERIES to be run from the script after tmp is updated (b,c,d)
-- ADD NEW MEMBERS
-- it should mostly fail (changes are slow and few)
-- this is logged via tr_insert_members
INSERT OR IGNORE INTO members(Name,LVL,Notes) SELECT Name, LVL, Notes FROM tmp;
-- DELETE OLD MEMBERS 
-- logged via tr_delete_members
DELETE FROM members WHERE Name NOT IN (SELECT Name FROM tmp);
-- EMPTY tmp at the end of the script run
DELETE FROM tmp;

当应用程序运行时，唯一需要调用的查询是：

a) 填充 tmp 的那个（来自 rvest 收集的数据框）
b) 从 tmp
添加新成员的查询 c) 查询删除不在 tmp
中的成员 d) 查询为空 tmp

这要归功于@forpas 友善建议的数据库设置。我从未使用过触发器，但终于对它们有了一些了解。对记录更改非常有帮助。

Answer 1

members_changes 的正确设计是这样的：

CREATE TABLE members_changes (
  timestamp TEXT DEFAULT CURRENT_TIMESTAMP,
  Id INTEGER REFERENCES members(Id),
  Name TEXT NOT NULL,
  LVL INTEGER NOT NULL,
  Notes TEXT
);

列 timestamp 的默认值为当前时间戳。

您需要 table tmp 的 AFTER INSERT 触发器，以便对于 tmp 中的每个插入行，来自成员的相应行将插入 members_changes（如果 LVL 或 Notes 的任何值不同），然后来自 tmp 的新行将更新 members 的行：

CREATE TRIGGER IF NOT EXISTS tr_insert_tmp AFTER INSERT ON tmp
BEGIN
  INSERT INTO members_changes(Id,Name,LVL,Notes)
  SELECT Id,Name,LVL,Notes
  FROM members
  WHERE Name = NEW.NAME AND (LVL IS NOT NEW.LVL OR Notes IS NOT NEW.Notes);
  
  UPDATE members 
  SET LVL = NEW.LVL, Notes = NEW.Notes
  WHERE Name = NEW.Name AND (LVL IS NOT NEW.LVL OR Notes IS NOT NEW.Notes);
END;

参见demo。

在 SQLite 中仅更新和记录 SQL 更改的行

Update and log only changed rows with SQL in SQLite

sql

sqlite

triggers

r

扩展答案概要

当应用程序运行时，唯一需要调用的查询是：