SQL 缺乏编程语言的灵活性和工具，这将为这个问题提供快速和优化的解决方案。
此外，在字符串操作方面，SQLite 是数据库中最差的，因为它不支持像 SQL Server 的 STRING_SPLIT() 或 MySql 的 SUBSTRING_INDEX() 这样非常有用的函数。
不过这个问题很有趣，我试了一下。
我用这个语句创建表dir_struct：
CREATE TABLE dir_struct (
Directory INTEGER PRIMARY KEY,
Directory_Parent INTEGER REFERENCES dir_struct(Directory),
Value TEXT
);
然后我插入'root' 行：
INSERT INTO dir_struct (Directory, Directory_Parent, Value) VALUES (0, null, 'root');
另外，我将OFF 外键强制执行为：
PRAGMA foreign_keys = OFF;
虽然默认是关闭的，以防万一。
首先，您需要一个递归 CTE，它将路径拆分到各个目录（很像您上一个问题的答案）。
然后在第二个 CTE 中，通过条件聚合，每个目录进入自己的列（最多 10 个目录）。
3d CTE 删除重复项，第 4 个 CTE 使用 ROW_NUMBER() 窗口函数为目录分配唯一 ID。
最后通过第 4 次 CTE 的结果的自连接，将行插入到表中：
WITH
split AS (
SELECT 0 idx,
FileDataID,
SUBSTR(SUBSTR(Path, 1), 1, INSTR(SUBSTR(Path, 1), '/') - 1) item,
SUBSTR(SUBSTR(Path, 1), INSTR(SUBSTR(Path, 1), '/') + 1) value
FROM listfile
UNION ALL
SELECT idx + 1,
FileDataID,
SUBSTR(value, 1, INSTR(value, '/') - 1),
SUBSTR(value, INSTR(value, '/') + 1)
FROM split
WHERE value LIKE '%_/_%'
),
cols AS (
SELECT DISTINCT
MAX(CASE WHEN idx = 0 THEN item END) path0,
MAX(CASE WHEN idx = 1 THEN item END) path1,
MAX(CASE WHEN idx = 2 THEN item END) path2,
MAX(CASE WHEN idx = 3 THEN item END) path3,
MAX(CASE WHEN idx = 4 THEN item END) path4,
MAX(CASE WHEN idx = 5 THEN item END) path5,
MAX(CASE WHEN idx = 6 THEN item END) path6,
MAX(CASE WHEN idx = 7 THEN item END) path7,
MAX(CASE WHEN idx = 8 THEN item END) path8,
MAX(CASE WHEN idx = 9 THEN item END) path9
FROM split
GROUP BY FileDataID
),
paths AS (
SELECT path0, path1, path2, path3, path4, path5, path6, path7, path8, path9 FROM cols UNION
SELECT path0, path1, path2, path3, path4, path5, path6, path7, path8, null FROM cols UNION
SELECT path0, path1, path2, path3, path4, path5, path6, path7, null, null FROM cols UNION
SELECT path0, path1, path2, path3, path4, path5, path6, null, null, null FROM cols UNION
SELECT path0, path1, path2, path3, path4, path5, null, null, null, null FROM cols UNION
SELECT path0, path1, path2, path3, path4, null, null, null, null, null FROM cols UNION
SELECT path0, path1, path2, path3, null, null, null, null, null, null FROM cols UNION
SELECT path0, path1, path2, null, null, null, null, null, null, null FROM cols UNION
SELECT path0, path1, null, null, null, null, null, null, null, null FROM cols UNION
SELECT path0, null, null, null, null, null, null, null, null, null FROM cols
),
ids AS (
SELECT *,
ROW_NUMBER() OVER (ORDER BY path0, path1, path2, path3, path4, path5, path6, path7, path8, path9) nr,
COALESCE(path9, path8, path7, path6, path5, path4, path3, path2, path1, path0) last_child,
path0 || COALESCE('/' || path1, '') ||
COALESCE('/' || path2, '') ||
COALESCE('/' || path3, '') ||
COALESCE('/' || path4, '') ||
COALESCE('/' || path5, '') ||
COALESCE('/' || path6, '') ||
COALESCE('/' || path7, '') ||
COALESCE('/' || path8, '') ||
COALESCE('/' || path9, '') full_path
FROM paths
)
INSERT INTO dir_struct(Directory, Directory_Parent, Value)
SELECT i1.nr, COALESCE(i2.nr, 0), i1.last_child
FROM ids i1 LEFT JOIN ids i2
ON i1.full_path = i2.full_path || '/' || i1.last_child
在包含 187365 行的测试数据集中，插入行的时间（平均）为 9.5-10 分钟，对于较大的数据集而言，这将更长。
请参阅demo。
更有趣的是，更简单的代码，性能更差（但你也可以测试一下）：
WITH
split AS (
SELECT Path,
0 parent_len,
SUBSTR(SUBSTR(Path, 1), 1, INSTR(SUBSTR(Path, 1), '/') - 1) item,
SUBSTR(SUBSTR(Path, 1), INSTR(SUBSTR(Path, 1), '/') + 1) value
FROM listfile
UNION ALL
SELECT Path,
parent_len + LENGTH(item) + 1,
SUBSTR(value, 1, INSTR(value, '/') - 1),
SUBSTR(value, INSTR(value, '/') + 1)
FROM split
WHERE value LIKE '%_/_%'
),
row_numbers AS (
SELECT parent_path, item,
ROW_NUMBER() OVER (ORDER BY parent_path, item) rn
FROM (SELECT DISTINCT SUBSTR(Path, 1, parent_len) parent_path, item FROM split)
)
INSERT INTO dir_struct(Directory, Directory_Parent, Value)
SELECT r1.rn, COALESCE(r2.rn, 0) rn_parent, r1.item
FROM row_numbers r1 LEFT JOIN row_numbers r2
ON r1.parent_path = r2.parent_path || r2.item || '/'
此查询分配给目录的 ID 与第一个解决方案分配的 ID 不同，但它们是正确且唯一的。
这运行（平均）14-15 分钟。
请参阅demo。
结论是，如果这是一次性的事情，也许你可以使用它，但我不推荐它作为这个要求的解决方案。