我创建了一个使用 MySQL 数据库的 Web 应用程序，但我必须将数据库迁移到Microsoft SQL Server 2008 R2并且我正在使用SQL Server 迁移助手(SSMA)。
对于某些使用外键的表，我的报告中出现错误。
1.自引用外键
我有一个表在行之间具有父子关系；地图表：
| map_id | map_title | latitude | longitude | map_zoom | map_parent |
|:------:|:-------------------:|:---------:|:----------:|:--------:|:----------:|
| 1 | My Parent Map | 50.364829 | -52.635623 | 17 | NULL |
| 2 | Some Child Map | 50.366916 | -52.634718 | | 1 |
| 3 | Another Child Map | 50.364898 | -52.634543 | | 1 |
| 4 | My Last Example Map | 50.361986 | -52.638891 | | 3 |
SQL Server 迁移助手 (SSMA) 生成的报告显示将用于在 SQL Server 中创建表的 SQL。
MySQL（来源）：
1 CREATE
2 TABLE `map`
3 (
4 `map_id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
5 `map_title` varchar(50) DEFAULT NULL,
6 `latitude` varchar(12) DEFAULT NULL,
7 `longitude` varchar(12) DEFAULT NULL,
8 `map_zoom` varchar(5) NOT NULL,
9 `map_parent` int(11) UNSIGNED DEFAULT NULL,
10 PRIMARY KEY (`map_id`) ,
11 KEY `map_parent` (`map_parent`) ,
12 CONSTRAINT `map_ibfk_2` FOREIGN KEY (`map_parent`) REFERENCES `map` (`map_id`) ON DELETE CASCADE ON UPDATE CASCADE
13 ) ENGINE = InnoDB AUTO_INCREMENT = 12 DEFAULT CHARSET = utf8;
SQL Server（目标，由 SSMA 生成的 SQL）：
1 CREATE TABLE dbo.map
2 (
3 map_id bigint NOT NULL IDENTITY(12, 1),
4 map_title nvarchar(50) NULL DEFAULT NULL,
5 latitude nvarchar(12) NULL DEFAULT NULL,
6 longitude nvarchar(12) NULL DEFAULT NULL,
7 map_zoom nvarchar(5) NOT NULL,
8 map_parent bigint NULL DEFAULT NULL,
9 CONSTRAINT PK_map_map_id PRIMARY KEY (map_id),
10 /*
11 * SSMA error messages:
12 * M2SS0040: ON DELETE CASCADE|SET NULL|SET DEFAULT action was changed to NO ACTION to avoid circular references of cascaded foreign keys.
13
14 CONSTRAINT map$map_ibfk_2 FOREIGN KEY (map_parent) REFERENCES dbo.map (map_id)
15 ON DELETE NO ACTION
16 /*
17 * SSMA error messages:
18 * M2SS0036: ON UPDATE CASCADE|SET NULL|SET DEFAULT action was changed to NO ACTION to avoid circular references of cascaded foreign keys.
19
20 ON UPDATE NO ACTION
21 */
22
23
24 */
25
26
27 )
28 GO
29 CREATE NONCLUSTERED INDEX map_parent
30 ON dbo.map (map_parent ASC)
31 GO
正如您所看到的，它给出了一个错误，表明它更改了 my ON UPDATE CASCADEandON DELETE CASCADE以NO ACTION “避免级联外键的循环引用”。
2.多对多表
我有两个表出现“多路径”错误，并且类似地更改为NO ACTION.
资产属性表：
| asset_id | property_id | property_value |
|:--------:|:-----------:|:---------------:|
| 933 | 1 | Joseph |
| 933 | 2 | Green |
| 936 | 1 | Jacob |
| 936 | 2 | Yellow |
| 942 | 1 | Susan |
| 942 | 2 | Blue |
MySQL（来源）：
1 CREATE
2 TABLE `asset_property`
3 (
4 `asset_id` int(11) NOT NULL,
5 `property_id` int(11) NOT NULL,
6 `property_value` varchar(100) DEFAULT NULL,
7 PRIMARY KEY (`asset_id`, `property_id`) ,
8 KEY `asset_id` (`asset_id`) ,
9 KEY `property_id` (`property_id`) ,
10 CONSTRAINT `asset_property_ibfk_1` FOREIGN KEY (`asset_id`) REFERENCES `asset` (`asset_id`) ON DELETE CASCADE ON UPDATE CASCADE ,
11 CONSTRAINT `asset_property_ibfk_2` FOREIGN KEY (`property_id`) REFERENCES `property` (`property_id`) ON DELETE CASCADE ON UPDATE CASCADE
12 ) ENGINE = InnoDB DEFAULT CHARSET = utf8;
SQL Server（目标，由 SSMA 生成的 SQL）：
1 CREATE TABLE dbo.asset_property
2 (
3 asset_id int NOT NULL,
4 property_id int NOT NULL,
5 property_value nvarchar(100) NULL DEFAULT NULL,
6 CONSTRAINT PK_asset_property_asset_id PRIMARY KEY (asset_id, property_id),
7 /*
8 * SSMA error messages:
9 * M2SS0041: ON DELETE CASCADE|SET NULL|SET DEFAULT action was changed to NO ACTION to avoid multiple paths in cascaded foreign keys.
10
11 CONSTRAINT asset_property$asset_property_ibfk_1 FOREIGN KEY (asset_id) REFERENCES dbo.asset (asset_id)
12 ON DELETE NO ACTION
13 /*
14 * SSMA error messages:
15 * M2SS0037: ON UPDATE CASCADE|SET NULL|SET DEFAULT action was changed to NO ACTION to avoid multiple paths in cascaded foreign keys.
16
17 ON UPDATE NO ACTION
18 */
19
20
21 */
22
23 ,
24 CONSTRAINT asset_property$asset_property_ibfk_2 FOREIGN KEY (property_id) REFERENCES dbo.property (property_id)
25 ON DELETE CASCADE
26 ON UPDATE CASCADE
27 )
28 GO
29 CREATE NONCLUSTERED INDEX asset_id
30 ON dbo.asset_property (asset_id ASC) 31 GO 32 CREATE NONCLUSTERED INDEX property_id
33 ON dbo.asset_property (property_id ASC) 34 GO
我只找到了一篇讨论这些错误的文章。文章对自引用表错误的解决方案似乎并不适用，而多对多错误解决方案只是删除约束“因为应用程序或用户不应该修改这些值”。
谢谢你的帮助！！
