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我正在开发用于学习外语的移动应用程序使用flutter和sqflite包装。该应用程序具有sqlite包含单词表和某种集合（多对多关系）的数据库。此数据存储在应用程序资产中，并在安装应用程序时加载到移动数据库目录，如 sqflite 指南https://github.com/tekartik/sqflite/blob/master/sqflite/doc/opening_asset_db.md
用户可以添加自己的文字和收藏，以及我希望能够填充或改变我的。我曾经认为我可以做到这一点，sqlite upsert但如果用户添加了与我在应用程序更新中所做的相同的词，就会出现冲突。如果我这样做了，upsert那么这个词就不会出现在我的单词集中，因为它们受 id 约束，否则，如果我这样做replace，然后单词从用户的收藏中消失。

我想我需要某种级联 id 更新sqlite insert or replace，但没有这样的功能。

请问有什么想法吗？

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1 回答 1

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我想我需要在 sqlite 插入或替换中进行某种级联 id 更新，但没有这样的功能。

有这样的特点；您指定ON UPDATE CASCADE为 FOREIGN KEY 定义/子句的一部分。您还可以编写ON DELETE CASCADE SQLite 外键支持 - 4.3。ON DELETE 和 ON UPDATE 操作。

因为这被编码为子表的一部分，并且您不能使用 ALTER TABLE COLUMN 来更改列的属性（除了重命名列）。你不得不 ：-

  1. 重命名子表。
  2. 使用更改后的原始名称创建替换表，然后使用 INSERT INTO replacement_table_with_original_name SELECT * FROM renamed_table（显然更改replacement_table_with_original_name和renamed_table）到实际名称。
  3. 当高兴 DROP 重命名的表。

例子

例如，考虑您的场景的以下表示（来自可用信息）然后这将添加ON UPDATE CASCADE并且ON DELETE CASCADE在保留现有数据的同时，它另外删除没有冲突的行，并且还更新引用的值而没有冲突或丢失：-

-- Create the original tables and load some test data
CREATE TABLE IF NOT EXISTS word_table (id INTEGER PRIMARY KEY, other_column TEXT);
INSERT INTO word_table VALUES (null,'WA'),(null,'WB'),(null,'WC');
CREATE TABLE IF NOT EXISTS collection_table (id INTEGER PRIMARY KEY, other_column TEXT);
INSERT INTO collection_table VALUES (null,'CA'),(null,'CB'),(null,'CC');
CREATE TABLE IF NOT EXISTS word_collection_map (
    word_reference INTEGER NOT NULL REFERENCES word_table(id), 
    collection_reference  INTEGER NOT NULL REFERENCES collection_table(id), 
    PRIMARY KEY (word_reference,collection_reference) ) WITHOUT ROWID;
INSERT INTO word_collection_map VALUES(1,1),(3,2),(3,3),(2,1),(2,2),(2,3);

-- show the result
SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
;

-- ADDING CASCADE
ALTER TABLE word_collection_map RENAME TO old_word_collection_map;
CREATE TABLE IF NOT EXISTS word_collection_map (
    word_reference INTEGER NOT NULL REFERENCES word_table(id) ON UPDATE CASCADE ON DELETE CASCADE , 
    collection_reference  INTEGER NOT NULL REFERENCES collection_table(id)  ON UPDATE CASCADE ON DELETE CASCADE, 
    PRIMARY KEY (word_reference,collection_reference) ) WITHOUT ROWID;
INSERT INTO word_collection_map SELECT * FROM old_word_collection_map;
DROP TABLE IF EXISTS old_word_collection_map;
-- Show results (should match first)
SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
;

-- DELETE a word no conflicts
DELETE FROM word_table WHERE other_column = 'WC';
SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
;

-- UPDATE the FK parent no conflicts
UPDATE collection_table SET id = 10 WHERE id = 3;
SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
;

结果 ：-

日志：-

-- Create the original tables and load some test data
CREATE TABLE IF NOT EXISTS word_table (id INTEGER PRIMARY KEY, other_column TEXT)
> OK
> Time: 0.118s


INSERT INTO word_table VALUES (null,'WA'),(null,'WB'),(null,'WC')
> Affected rows: 3
> Time: 0.104s


CREATE TABLE IF NOT EXISTS collection_table (id INTEGER PRIMARY KEY, other_column TEXT)
> OK
> Time: 0.097s


INSERT INTO collection_table VALUES (null,'CA'),(null,'CB'),(null,'CC')
> Affected rows: 3
> Time: 0.094s


CREATE TABLE IF NOT EXISTS word_collection_map (
    word_reference INTEGER NOT NULL REFERENCES word_table(id), 
    collection_reference  INTEGER NOT NULL REFERENCES collection_table(id), 
    PRIMARY KEY (word_reference,collection_reference) ) WITHOUT ROWID
> OK
> Time: 0.097s


INSERT INTO word_collection_map VALUES(1,1),(3,2),(3,3),(2,1),(2,2),(2,3)
> Affected rows: 6
> Time: 0.105s


-- show the result
SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
> OK
> Time: 0.001s


-- ADDING CASCADE
ALTER TABLE word_collection_map RENAME TO old_word_collection_map
> OK
> Time: 0.108s


CREATE TABLE IF NOT EXISTS word_collection_map (
    word_reference INTEGER NOT NULL REFERENCES word_table(id) ON UPDATE CASCADE ON DELETE CASCADE , 
    collection_reference  INTEGER NOT NULL REFERENCES collection_table(id)  ON UPDATE CASCADE ON DELETE CASCADE, 
    PRIMARY KEY (word_reference,collection_reference) ) WITHOUT ROWID
> OK
> Time: 0.096s


INSERT INTO word_collection_map SELECT * FROM old_word_collection_map
> Affected rows: 6
> Time: 0.094s


DROP TABLE IF EXISTS old_word_collection_map
> OK
> Time: 0.081s


-- Show results (should match first)
SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
> OK
> Time: 0s


-- DELETE a word no conflicts
DELETE FROM word_table WHERE other_column = 'WC'
> Affected rows: 1
> Time: 0.086s


SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
> OK
> Time: 0.001s


-- UPDATE the FK parent no conflicts
UPDATE collection_table SET id = 10 WHERE id = 3
> Affected rows: 1
> Time: 0.089s


SELECT word_table.other_column, collection_table.other_column 
FROM word_collection_map 
    JOIN word_table ON word_table.id = word_reference
    JOIN collection_table ON collection_table.id = collection_reference
> OK
> Time: 0s

结果 1（基础数据）

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结果 2（架构更改后）

在此处输入图像描述

结果 3（删除后）

在此处输入图像描述

结果4（更新后）

在此处输入图像描述

于 2019-07-10T21:17:51.440 回答